What is Bitcoin?

TL;DR: Bitcoin is a decentralized digital money system that allows anyone to send value to anyone else without permission from a bank, government, or any third party. It has a fixed supply of 21 million bitcoin, enforced by code and verified by a global network of nodes. Bitcoin operates on proof-of-work consensus, making it the most secure and censorship-resistant monetary network ever built.

Bitcoin is an open-source, peer-to-peer electronic cash system that enables direct value transfer between parties without relying on a trusted intermediary. The Bitcoin network is secured by proof-of-work mining and maintained by thousands of independently operated nodes across the globe. Its monetary supply is capped at 21 million bitcoin, a hard limit produced by the block subsidy schedule and enforced by every node on the network; the MAX_MONEY ceiling in Bitcoin Core's src/consensus/amount.h expresses that cap in code. It has been embedded in the protocol since its creation in 2009.

Understanding Bitcoin

Bitcoin is money that works without asking permission. No bank approves your transaction, no government issues or controls it, and no company runs it. The rules are enforced by software, and anyone on Earth can participate by running that software.

At its most fundamental level, Bitcoin is a protocol: a set of rules that computers follow to maintain a shared record of who owns what. That record is called the blockchain, a chain of cryptographic blocks linking every transaction back to the network's first block, mined by its pseudonymous creator Satoshi Nakamoto on January 3, 2009.

Every ten minutes, on average, the network produces a new block. This interval is set by nPowTargetSpacing (600 seconds) in Bitcoin Core's src/kernel/chainparams.cpp. Each block contains a batch of transactions and a cryptographic link to the previous block. Because every block references the one before it, altering any historical transaction would require redoing the work for every subsequent block, an amount of energy expenditure that quickly becomes economically and computationally infeasible.

Bitcoin is both the network (capital B) and the money that moves on it (lowercase b). The Bitcoin protocol defines how the system works. The bitcoin you control exists as spendable outputs recorded on that system, and only your cryptographic keys can unlock them.

Unlike every monetary system that came before it, Bitcoin requires no trust in any specific institution. The money supply follows a fixed protocol schedule instead of a central bank's discretion, and users hold their own funds instead of relying on a bank to keep them safe. Transactions settle directly across the network, without a payment processor relaying them. The system replaces institutional trust with mathematical verification.

Why This Matters

Every monetary system before Bitcoin required trust in intermediaries, and Bitcoin was designed to remove the failure points that trust creates. Citizens trust governments not to inflate the currency, depositors trust banks not to lend recklessly with their funds, and merchants trust payment networks to settle honestly. When that trust breaks down, people suffer: savings evaporate, accounts freeze, and transactions get reversed or blocked.

Decentralization

Bitcoin is not a company: there is no central leadership or corporate infrastructure behind it. The network is maintained by thousands of independent computers, called nodes, spread across every continent. Each node stores a complete copy of the blockchain and independently validates every transaction against the protocol's rules.

Decentralization is the source of every other property that makes Bitcoin valuable.

A centralized system has a single point of failure. A government can pressure a company to block transactions, a CEO can change the rules, a data center can be raided, and a server can go down. Bitcoin has none of these vulnerabilities because there is no center to attack, pressure, or shut down.

How Decentralization Works in Practice

Every Bitcoin node independently validates every block and every transaction. If a miner produces a block that violates the rules (for example, trying to create bitcoin beyond the supply schedule, or spending funds that have already been spent), every node on the network rejects that block automatically. No meeting is held. No committee votes. The software enforces the rules without human intervention.

As of early 2026, there are roughly 22,000 publicly reachable Bitcoin nodes across the globe. The total is far higher: counting nodes that operate behind firewalls or over the Tor network and are not publicly visible, estimates run to 60,000 or more. Each one of these nodes independently enforces the protocol. To change Bitcoin's rules, you would need the overwhelming voluntary cooperation of thousands of independent operators who have economic incentives to resist any change that threatens the network's properties.

Independent enforcement is what makes Bitcoin different from every digital payment system that came before it. PayPal, Venmo, and banking apps all process your transactions through a single company's servers. If that company decides you cannot use its service, your access ends. If that company's servers go down, you cannot transact. Bitcoin has no such chokepoint.

What Decentralization Means for Institutions

For financial institutions, Bitcoin's decentralization is a feature, not a liability. A decentralized settlement network carries no counterparty risk from a single operator. No company can change the protocol's monetary policy, alter transaction history, or restrict access. These properties make Bitcoin uniquely suited as a neutral settlement layer that does not require trusting any single entity with control over the infrastructure.

Fixed Supply: 21 Million Bitcoin

There will never be more than 21 million bitcoin. This limit is produced by the halving schedule and enforced by every node on the network; the MAX_MONEY ceiling in Bitcoin Core's src/consensus/amount.h expresses it in code. No single authority can change that limit or create more bitcoin.

This fixed supply is the most radical departure from how money has worked for the past century. Every government-issued (fiat) currency operates on the assumption that a central authority can and should adjust the money supply as it sees fit. The U.S. Federal Reserve, the European Central Bank, and every other central bank on Earth can create new units of currency at will. Bitcoin cannot.

The Issuance Schedule

New bitcoin enters circulation through a process called mining. When a miner produces a valid block, the protocol rewards them with newly created bitcoin. This reward, called the block subsidy, follows a precise and predictable schedule:

Every 210,000 blocks (approximately every four years), the block subsidy cuts in half. The interval is defined by nSubsidyHalvingInterval in src/kernel/chainparams.cpp. This event is called the halving. The most recent halving occurred in April 2024, reducing the subsidy from 6.25 to 3.125 bitcoin per block. The halvings will continue until approximately the year 2140, when the last fraction of a bitcoin will be mined and the total supply will reach its final count of 21 million.

Under the Hood: Where the 21 Million Comes From

The 21 million cap is not an arbitrary number stored in a configuration file. It is the mathematical result of the halving schedule. The total supply is a geometric series: each era produces 210,000 blocks, and the reward per block halves each era. The sum is:

210,000 × 50 × (1 + 1/2 + 1/4 + 1/8 + ...) = 210,000 × 50 × 2 = 21,000,000

The infinite geometric series (1 + 1/2 + 1/4 + ...) converges to exactly 2. Multiplied by the first era's total output (210,000 blocks × 50 bitcoin), the result is precisely 21 million. Because bitcoin amounts are denominated in satoshis (integer units of 1/100,000,000 BTC), the actual total falls just short of 21 million due to rounding at the smallest denomination. The difference is negligible: the true total is approximately 20,999,999.98 bitcoin, fewer than one full bitcoin short of the round 21 million figure.

Every full node enforces this supply by checking each block's coinbase transaction against the expected subsidy for that block height. The function GetBlockSubsidy() in Bitcoin Core's src/validation.cpp performs this calculation: it takes the block height, divides by nSubsidyHalvingInterval (210,000) to determine the current era, then right-shifts the initial subsidy of 50 BTC accordingly. Any block that awards more than the calculated amount is rejected by every honest node on the network.

By February 2026, approximately 19.98 million bitcoin have already been mined. Over 94% of all the bitcoin that will ever exist is already in circulation. The remaining 1 million bitcoin will be distributed over the next 114 years at an ever-decreasing rate.

Why Fixed Supply Matters

When a central bank increases the money supply, each existing unit of currency represents a smaller share of total purchasing power. That erosion is inflation. Between 2020 and 2023 alone, the U.S. M2 money supply expanded by roughly 40%, and every dollar in circulation lost value as a result.

Bitcoin's supply cannot be inflated. The code does not contain a function for creating bitcoin outside of the mining schedule, and the entire network of nodes verifies that no such creation occurs. For anyone seeking to preserve purchasing power over long time horizons, this property is significant. You can know, with mathematical certainty, exactly how much bitcoin exists today and how much will exist at any point in the future.

Institutional Perspective on Scarcity

For institutional investors and corporate treasuries, Bitcoin's fixed supply introduces a monetary asset with a verifiable scarcity that gold cannot match. Gold's above-ground supply increases by approximately 1.5% per year, with no hard cap. Seabed mining, asteroid mining, and new deposit discoveries could accelerate that rate. Bitcoin's supply schedule, by contrast, is fully predictable and cryptographically enforced. This has driven corporate treasury adoption: MicroStrategy (now Strategy) holds more than 818,000 bitcoin on its balance sheet (as of its Q1 2026 10-Q), treating it as a primary treasury reserve asset.

Censorship Resistance

No one can prevent you from sending or receiving bitcoin. No entity can freeze your balance, reverse your transaction, or deny you access to the network.

Consider these real-world scenarios:

• Bank account freezes: In 2022, the Canadian government ordered banks to freeze accounts of individuals associated with protests. Accounts were locked without court orders. Bitcoin held in self-custody would have been unaffected.
• Capital controls: Citizens of countries with strict capital controls (Nigeria, China, Argentina, Turkey) cannot freely move their savings across borders through the banking system. Bitcoin transactions cross borders the same way an email does: instantly, without gatekeepers.
• De-banking: Financial institutions routinely close accounts of individuals, businesses, and entire industries based on internal risk assessments, sometimes with no explanation. If your money exists only as a record at a bank, the bank's decision is final. Bitcoin held with your own keys is under your control alone.

Censorship resistance emerges directly from decentralization. Because no single entity controls the Bitcoin network, no single entity can impose restrictions on who uses it. A transaction broadcast to the network will be included in a block by whichever miner finds the next valid block. Transactions carry no built-in identity information, and miners have a strong economic incentive to include every valid, fee-paying transaction regardless of origin.

Self-Custody: The Foundation of Financial Sovereignty

Censorship resistance depends on self-custody. If your bitcoin sits on an exchange, the exchange can freeze your account. Only when you hold your own keys does the full promise of Bitcoin's censorship resistance apply to you. A self-custodial wallet like the Blockstream app gives you direct control of your bitcoin, with no exchange or intermediary standing between you and your funds.

Self-custody means holding your own private keys. The private key is a cryptographic secret that proves ownership of bitcoin on the network. When you hold the key, only you can authorize transactions. When someone else holds the key (an exchange, a bank, a custodian), they control your funds, and your access depends on their continued willingness to provide it.

Why Bitcoin Was Created

On October 31, 2008, Satoshi Nakamoto, the individual or group behind the pseudonym, published a nine-page whitepaper titled "Bitcoin: A Peer-to-Peer Electronic Cash System". The paper opened with a clear diagnosis:

"Commerce on the Internet has come to rely almost exclusively on financial institutions serving as trusted third parties to process electronic payments. While the system works well enough for most transactions, it still suffers from the inherent weaknesses of the trust based model."

The timing was deliberate. In September 2008, Lehman Brothers collapsed and the global financial system went into free fall, with banks that had been deemed "too big to fail" failing. Governments responded with massive bailouts funded by newly printed money, transferring the costs of institutional recklessness to ordinary citizens through inflation and austerity.

Satoshi embedded a message in Bitcoin's very first block, the genesis block mined on January 3, 2009:

"The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"

This headline from the front page of The Times of London was a statement of purpose, not mere metadata. Bitcoin was created in direct response to the failure of trusted institutions: central banks, commercial banks, and the regulatory systems that were supposed to prevent catastrophe but did not.

The Problem Bitcoin Solves

Before Bitcoin, sending money digitally required trusting an intermediary. If you wanted to pay someone online, a bank or payment processor had to sit between you and the recipient. That intermediary could reverse the transaction, block it, charge fees, delay settlement, or exclude you entirely.

Physical cash solves this problem in person. When you hand someone a bill, the transaction is final, immediate, and requires no trust beyond the integrity of the currency itself. But physical cash does not work over the internet. You cannot email a dollar bill.

Bitcoin created digital cash: a payment system that is final like physical cash but works over the internet, settling directly between the two parties with no intermediary and no way to reverse a payment. The whitepaper described it as "a purely peer-to-peer version of electronic cash" that "would allow online payments to be sent directly from one party to another without going through a financial institution".

How Bitcoin Compares to Other Forms of Money

Money, regardless of its form, is evaluated against a set of properties: scarcity, divisibility, portability, durability, verifiability, and fungibility. These properties determine how well a monetary good works as a store of value, a medium of exchange, and a unit of account. Bitcoin was designed to excel at each one.

The comparison reveals a consistent pattern. Bitcoin matches or exceeds gold in the properties that matter for a store of value (scarcity, durability, verifiability), while dramatically outperforming it in the properties that matter for a medium of exchange (divisibility, portability). Fiat currency remains more widely accepted as a daily medium of exchange, but its persistent inflation undermines its function as a store of value over any meaningful time horizon.

What Determines Bitcoin's Price

Bitcoin has no central issuer setting its price. Its market value is determined entirely by supply and demand across thousands of exchanges, brokerages, and over-the-counter desks worldwide. The supply side is fixed by code: roughly 19.98 million bitcoin exist today, and the issuance rate is known decades in advance. The demand side is where the price moves.

Several forces shape demand at any given moment:

• Adoption and capital flows. Spot ETF inflows, corporate treasury purchases, and new retail users add buying pressure; outflows and selling reduce it.
• Macroeconomic conditions. Interest rates, inflation expectations, and currency debasement affect how attractive a fixed-supply asset looks relative to bonds, equities, and cash.
• The halving cycle. Every 210,000 blocks, the rate of new issuance drops by half. Past cycles have shown shifting supply-demand dynamics around these events, though no outcome is guaranteed and past performance does not predict future results.
• Liquidity and market structure. The depth of order books and the availability of regulated venues affect how easily large orders move the price.

Because demand is driven by sentiment, news, and global capital allocation, the price can be volatile over short horizons. One bitcoin is divisible into 100 million satoshis, so the unit price never limits participation: a buyer can acquire any fraction. To check the current price and on-chain activity, a block explorer such as Blockstream Explorer shows live network data, while exchanges publish real-time quotes.

Bitcoin vs. Other Digital Assets

Bitcoin is frequently grouped with thousands of other digital assets under the umbrella term "crypto". This grouping obscures fundamental differences in design, purpose, security, and monetary policy that make Bitcoin categorically distinct.

Different Monetary Policy

Bitcoin's 21 million supply cap cannot be changed. This is not a governance decision; it is a protocol rule enforced by every node on the network. Most other digital assets have flexible or inflationary supply models controlled by founding teams, foundations, or governance votes. Ethereum's monetary policy has changed multiple times since its launch. Many other tokens can be minted at will by their creators.

Different Security Model

Bitcoin is secured by proof-of-work mining, which requires real-world energy expenditure. As of early 2026, the Bitcoin network's cumulative hashrate makes it the most computationally secured system in human history. This energy expenditure creates a physical cost to attacking the network. Most other digital assets use proof-of-stake or delegated consensus mechanisms that do not carry equivalent physical costs and concentrate validation power among large token holders.

Different Development Philosophy

Bitcoin's development process prioritizes stability, backward compatibility, and extreme caution. Protocol changes require overwhelming consensus across developers, miners, node operators, and the broader economic network. This conservative approach means Bitcoin evolves slowly, but it also means the rules you rely on today will still be there tomorrow.

Most other digital assets move fast, ship frequently, and break backward compatibility. This agility has trade-offs: frequent hard forks, governance disputes, and rule changes that can affect existing holders without their consent.

No Company Behind It

There is no "Bitcoin Inc." Satoshi Nakamoto disappeared from public communication in 2011. No individual, company, or foundation controls Bitcoin's development, marketing, or roadmap. The protocol is maintained by a decentralized community of open-source developers, reviewed publicly, and adopted voluntarily by node operators.

Most other digital assets have identifiable founders, venture capital backing, foundations with treasuries, and marketing teams. This creates accountability, but it also creates centralized points of influence, legal liability, and single points of failure.

Why Bitcoin-Only Strategies Are Growing

An increasing number of financial advisors, family offices, and institutional investors operate Bitcoin-only strategies. The reasoning is straightforward: Bitcoin's decentralization, fixed supply, and proof-of-work security model provide properties that no other digital asset replicates. For an investor seeking a scarce, censorship-resistant, decentralized store of value, Bitcoin is the only asset in the category that fully delivers on those properties.

Why Institutions Are Adopting Bitcoin

Institutional adoption of Bitcoin has accelerated dramatically since 2024. The approval of spot Bitcoin ETFs in the United States in January 2024 removed one of the last major barriers to institutional participation. By early 2026, Bitcoin ETFs had attracted approximately $58 billion in cumulative net inflows, making them the most successful ETF launch category in history.

What Changed

Several developments converged to move Bitcoin from the fringe of institutional finance to its center:

• Regulatory clarity: The SEC's approval of spot Bitcoin ETFs in January 2024 gave institutions a regulated, familiar vehicle for Bitcoin exposure. This eliminated the custody, compliance, and operational concerns that had kept many allocators on the sidelines.
• Accounting standards: The FASB's update to fair value accounting for digital assets (effective for fiscal years beginning after December 15, 2024) allowed companies to mark bitcoin holdings to market value on their balance sheets. Under the prior rules, companies could only write down bitcoin's value but never write it up, creating artificial losses that discouraged corporate adoption.
• Corporate treasury adoption: MicroStrategy's multi-year bitcoin accumulation strategy, which began in August 2020, demonstrated that a publicly traded company could hold bitcoin as a primary reserve asset. By early 2026, the company holds more than 818,000 bitcoin. Other public companies, including Tesla, Block, and dozens of smaller firms, followed with their own treasury allocations.
• Banking infrastructure: Major banks and financial institutions are building Bitcoin custody, trading, and lending services. The infrastructure that institutions require (prime brokerage, qualified custody, regulated order execution) now exists across multiple regulated providers.

Bitcoin's Regulatory Status

Bitcoin occupies a unique position among regulated assets. The CFTC has classified Bitcoin as a commodity since 2015, and the SEC's approval of spot Bitcoin ETFs further solidified this classification. This distinction matters because most other digital assets face ongoing securities classification debates that create legal uncertainty for institutions.

For financial institutions evaluating digital asset strategies, Bitcoin's clear commodity classification reduces legal risk and simplifies compliance. Bitcoin was the first digital asset with approved spot ETFs in the United States, and it has a consistent regulatory classification across major jurisdictions.

Why Bitcoin Is the Institutional Entry Point

Institutions entering the digital asset space overwhelmingly start with Bitcoin. The reasons are structural:

• Deepest liquidity: Bitcoin consistently accounts for over 50% of total digital asset market capitalization, with daily trading volume across exchanges, ETFs, and OTC desks measured in the tens of billions.
• Longest track record: Bitcoin has operated continuously since January 2009. Over 17 years of near-continuous operation with no lasting protocol-level compromise.
• Clearest regulatory status: Commodity classification. Spot ETF approval. No ongoing securities litigation.
• Most mature custody solutions: Institutional custody infrastructure for Bitcoin is well established, with qualified custodians offering segregated cold storage, insurance, and SOC2-audited operations.
• Simplest thesis: Scarce digital asset with a fixed supply and growing adoption. The investment case does not require evaluating smart contract platforms, lending-protocol yields, or token utility models.

How Bitcoin Works

Understanding Bitcoin at a conceptual level requires grasping four components: transactions, blocks, mining, and nodes. Each component plays a distinct role in keeping the system secure, honest, and functional.

Transactions

A Bitcoin transaction is a signed message that transfers ownership of bitcoin from one address to another. When you send bitcoin, you are creating a digital message that says, in essence: "I authorize moving X bitcoin from address A to address B". You sign this message with your private key, which proves you own the bitcoin at address A.

The signed transaction is broadcast to the Bitcoin network. Nodes receive it, verify that the signature is valid and the sender has sufficient funds, and relay it to other nodes. That signature comes from one of two schemes: ECDSA (used by legacy and SegWit v0 outputs, still the majority of new outputs today) and Schnorr (BIP 340, used by Taproot outputs since its activation in November 2021). At this point, the transaction is unconfirmed. It sits in a waiting area called the mempool until a miner includes it in a block.

Blocks

A block is a bundle of transactions. Approximately every ten minutes, a miner assembles a set of valid, unconfirmed transactions from the mempool into a candidate block. The block also contains a reference (hash) to the previous block, linking it into the chain. This chain of cryptographic references is what gives the "blockchain" its name and its security.

Each block has a maximum weight of 4 million weight units (4 MWU), defined as MAX_BLOCK_WEIGHT in Bitcoin Core's src/consensus/consensus.h, with typical blocks containing roughly 1.5 to 2 MB of serialized data. This constraint means that when demand for block space is high, transactions compete for inclusion by offering higher fees. Miners prioritize higher-fee transactions because they are economically incentivized to maximize their revenue.

Mining

Mining is the process that secures the Bitcoin network and produces new blocks. Miners compete to find a block whose header hashes to a value below the current difficulty target. Finding one means repeatedly hashing the block header, changing a nonce with each attempt, until the result falls below the target, at a rate of trillions of attempts per second. The only way to get there is brute-force computation. There is no shortcut.

The first miner to find a valid solution broadcasts the new block to the network. Other nodes verify the solution (which is trivial to check but hard to find), validate every transaction in the block, and add it to their copy of the blockchain. The winning miner receives the block subsidy (currently 3.125 bitcoin) plus all the transaction fees from the transactions included in the block.

This is proof-of-work in action. The "work" is the energy spent on computation. The "proof" is the valid solution that anyone can verify. This mechanism ensures that producing blocks has a real-world cost, which makes attacking the network prohibitively expensive.

Nodes

Nodes are the enforcers. A Bitcoin node is a computer running the Bitcoin software that stores a complete copy of the blockchain and independently validates every transaction and every block against the protocol's rules. Nodes do not trust miners, other nodes, or any external authority. They verify everything independently. If a block breaks a consensus rule, every node rejects it, regardless of which miner produced it. Miners decide the order of transactions; nodes decide whether a block is valid at all.

When you run a node, you do not need to trust anyone's claim about the state of the blockchain. Your node has verified every transaction from the genesis block to the present moment. This independent verification by thousands of nodes worldwide is what makes Bitcoin trustless: you do not need to trust because you can verify. For quick on-demand verification without running a full node, Blockstream Explorer lets you look up any transaction, block, or address on the Bitcoin network.

Hardware wallets like the Jade Plus keep your private keys on a dedicated device, isolated from internet-connected computers. When you combine a hardware wallet with a personal node, you achieve the highest level of Bitcoin security and sovereignty: your keys never touch an online device, and your transactions are verified by your own copy of the blockchain.

Layer-2 Networks

The Bitcoin base layer prioritizes security and decentralization over transaction speed. The roughly ten-minute block interval and limited block size mean the base layer processes a limited number of transactions per block (typically 2,000-4,000 depending on transaction type). This is a deliberate engineering trade-off: the base layer is a settlement layer, like the Federal Reserve's Fedwire system, not a point-of-sale payment rail.

For faster and cheaper transactions, layer-2 networks build on top of Bitcoin's base layer, each with its own security model. The Lightning Network enables near-instant bitcoin payments with minimal fees by creating payment channels between participants. The Liquid Network, a federated sidechain built by Blockstream, provides faster block times (approximately one minute), Confidential Transactions that hide both transaction amounts and asset types from outside observers, and the ability to issue additional assets like stablecoins and security tokens.

These layer-2 networks allow Bitcoin to scale while keeping the base layer maximally secure and decentralized. To use all three layers in one place, the Blockstream app provides access to Bitcoin, Lightning, and Liquid in a single interface, paired with the Jade Plus hardware wallet for self-custodial security. For the mechanics behind each step, see How Does Bitcoin Work?

Frequently Asked Questions

Is Bitcoin real money?

Bitcoin functions as money: it can be used to send value, store purchasing power, and price goods and services. It was recognized as legal tender in El Salvador from 2021 to 2025 (legal tender status was repealed in January 2025 as a condition of IMF lending; merchant adoption continues), is classified as a commodity by the CFTC, and has approved spot ETFs in the United States. Hundreds of millions of people worldwide hold bitcoin in some form. Whether something qualifies as "real money" depends on the definition used, but by the most common economic criteria (store of value, medium of exchange, unit of account), Bitcoin meets all three.

Who controls Bitcoin?

No single person, company, or government controls Bitcoin. The network is maintained by thousands of independent nodes worldwide, and protocol changes require overwhelming voluntary consensus from developers, miners, and node operators. Satoshi Nakamoto, Bitcoin's pseudonymous creator, has been inactive since 2011. There is no "Bitcoin Inc." or central authority.

Can Bitcoin be hacked or shut down?

The Bitcoin protocol has never been permanently compromised in over 17 years of continuous operation, though several consensus bugs have been discovered and patched. The network is secured by more computational power than any other system in existence. Shutting down Bitcoin would require simultaneously shutting down tens of thousands of independent computers in every jurisdiction on Earth, including those connected via satellite. Individual wallets and exchanges can be compromised through poor security practices, but the protocol itself has proven resistant to attack.

How many bitcoin will ever exist?

21 million. This cap is not a configurable setting; it is the mathematical result of the halving schedule. The block subsidy starts at 50 bitcoin and halves every 210,000 blocks, producing a geometric series: 210,000 × 50 × (1 + 1/2 + 1/4 + ...) = 21,000,000. The series converges to precisely 21 million. Every full node enforces this limit by rejecting any block whose coinbase transaction exceeds the allowed subsidy for that block height. The constant MAX_MONEY in Bitcoin Core's src/consensus/amount.h defines the cap as 2,100,000,000,000,000 satoshis (21 million × 100 million satoshis per bitcoin).

How is Bitcoin different from other digital assets?

Bitcoin has a fixed supply of 21 million, is secured by proof-of-work mining (requiring real energy expenditure), and has no company, foundation, or identifiable leader controlling its development. Most other digital assets have flexible supply models, use less energy-intensive consensus mechanisms, and are managed by identifiable teams or foundations. Bitcoin also has the longest track record (since 2009), deepest liquidity, and clearest regulatory classification as a commodity.

How much bitcoin do I need to get started?

You do not need to buy a whole bitcoin. One bitcoin is divisible into 100 million satoshis (sats), as defined by the COIN constant (100,000,000) in Bitcoin Core's src/consensus/amount.h. You can buy any amount you choose. Many people start with small, regular purchases. There is no minimum investment required by the Bitcoin protocol itself, though individual exchanges and apps may have their own minimums.

Is Bitcoin bad for the environment?

Bitcoin mining consumes energy, and that energy expenditure is what secures the network. Increasingly, miners seek out the cheapest energy sources, which frequently means renewable or stranded energy that would otherwise go unused (flared natural gas, excess hydroelectric, curtailed solar and wind). Studies estimate that Bitcoin mining's sustainable energy mix is roughly 50-60%, with recent independent estimates near the lower end of that range. The energy cost also provides a measurable, physical security guarantee that alternative consensus mechanisms do not offer.

How much is one bitcoin worth?

Bitcoin's price is set by supply and demand across global exchanges, not by any central issuer, so it changes continuously. There is no need to buy a whole unit: one bitcoin divides into 100 million satoshis, and you can buy any fraction. For a live figure, check a regulated exchange or on-chain data through a block explorer such as Blockstream Explorer. Prices can be volatile over short horizons, so verify the current rate before transacting.

When did Bitcoin start?

The Bitcoin whitepaper was published on October 31, 2008, and the network launched when Satoshi Nakamoto mined the genesis block on January 3, 2009. The first Bitcoin transaction, from Satoshi to developer Hal Finney, occurred on January 12, 2009. Bitcoin has operated continuously since then, making it the longest-running monetary network of its kind with over 17 years of continuous operation.