[Crypto projects](https://revain.org/projects/) › Bitcoin

# Bitcoin (BTC): how it works, supply and reviews

Layer 1 blockchain

## In short

- **Type**: Independent layer-1 blockchain with its own peer-to-peer network
- **Maximum supply**: 21,000,000 BTC
- **Risks and caveats**: Bitcoin transactions are irreversible once confirmed.
- **Checked**: 28 October 2026

## Key facts

- **Ticker**: BTC
- **Category**: Layer 1 blockchain
- **Network**: own blockchain
- **Launched**: 2009-01
- **Mining algorithm**: SHA-256
- **Official site**: [bitcoin.org](http://www.bitcoin.org)
- **Whitepaper**: [bitcoin.org/bitcoin.pdf](https://bitcoin.org/bitcoin.pdf)
- **Source code**: [github.com/bitcoin/bitcoin](https://github.com/bitcoin/bitcoin)

Data: CoinGecko, 2026-10-27. Only projects that still trade with meaningful volume are listed.

## What is Bitcoin

Bitcoin is a peer-to-peer electronic cash system that lets payments move directly between people without a bank or other central authority. Transactions are recorded on a public blockchain secured by proof-of-work mining, and BTC is the network's native currency.

## Network and consensus

| Parameter | Details |
|---|---|
| Type | Independent layer-1 blockchain with its own peer-to-peer network |
| Consensus | Proof of work (mining); the longest valid chain is followed |
| Launched | Genesis block timestamped 3 January 2009 |
| Block time | About 10 minutes on average; mining difficulty adjusts automatically to keep this pace |
| Smart contracts | Limited scripting: outputs are locked by scripts such as multi-signature conditions |

## Supply and issuance

| Parameter | Details |
|---|---|
| Maximum supply | 21,000,000 BTC |
| Issuance | New BTC are paid to miners in each block at a fixed, decreasing rate until issuance stops |
| Halving | The block subsidy halves every 210,000 blocks (roughly every four years) |
| Initial distribution | No pre-sale: the first block paid a 50 BTC subsidy, and all BTC enter circulation through mining |

## What BTC is used for

- Sending and receiving payments directly between users
- Paying transaction fees to miners
- Rewarding miners, together with newly issued BTC, for securing the network

## Who develops and governs Bitcoin

- **Founders**: Created by the pseudonymous Satoshi Nakamoto, who left the project in late 2010
- **Governance**: No company or foundation controls it; changes are proposed publicly as BIPs and take effect only if users, miners and node operators adopt them
- **Developer**: Bitcoin Core, an open-source project descended from the original client, is the main reference software
- **Open source**: Yes; Bitcoin Core is released under the MIT license

## History

| Date | Event |
|---|---|
| 3 January 2009 | Genesis block created with the embedded headline "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks". |
| 2009 | Satoshi Nakamoto publishes the first Bitcoin specification and proof of concept on a cryptography mailing list. |
| 2010 | Satoshi Nakamoto leaves the project; development continues through an open community of contributors. |

## Security and audits

- Bitcoin Core publishes a vulnerability disclosure policy; issues are reported to security@bitcoincore.org and assigned a severity class.
- Security flaws have been found and fixed in software implementations over time; the protocol rules themselves have run since 2009.
- Losses on exchanges and businesses did not involve the Bitcoin protocol itself; the most common risk is user error, such as lost or stolen wallet keys.

## Risks and caveats

- Bitcoin transactions are irreversible once confirmed.
- Whoever holds the private keys controls the funds; lost or stolen keys mean lost coins.
- Legal treatment differs by country: some jurisdictions restrict or ban its use, and rules continue to change.
- Quantum computers able to break Bitcoin's cryptography do not exist yet; the protocol would need an upgrade if that changed.

## Official links

- Website: [bitcoin.org/en](https://bitcoin.org/en/)
- Whitepaper: [bitcoin.org/bitcoin.pdf](https://bitcoin.org/bitcoin.pdf)
- Source code: [github.com/bitcoin/bitcoin](https://github.com/bitcoin/bitcoin)
- Docs: [developer.bitcoin.org/devguide/block_chain.html](https://developer.bitcoin.org/devguide/block_chain.html)

## Questions and answers

**What is Bitcoin?**

Bitcoin is a peer-to-peer electronic cash system that runs without a bank or central authority. BTC is its native currency.

**Who created Bitcoin?**

Bitcoin was created by the pseudonymous Satoshi Nakamoto, who published the first specification and proof of concept in 2009 and left the project in late 2010.

**What is the maximum supply of Bitcoin?**

Only 21 million BTC will ever be created. The block subsidy halves every 210,000 blocks until issuance stops.

**How does Bitcoin reach consensus?**

Miners compete to produce proof of work for each block, and difficulty adjusts so a block is found about every 10 minutes on average.

**Who controls Bitcoin?**

No single person or group. Protocol changes are proposed publicly and take effect only if users, miners and node operators choose to adopt them.

## Sources

- [CoinGecko — Bitcoin](https://www.coingecko.com/en/coins/bitcoin)
- [Bitcoin: A Peer-to-Peer Electronic Cash System (whitepaper)](https://bitcoin.org/bitcoin.pdf)
- [Bitcoin.org — Frequently Asked Questions](https://bitcoin.org/en/faq)
- [Bitcoin.org — home page](https://bitcoin.org/en/)
- [Bitcoin Core — About](https://bitcoincore.org/en/about/)
- [Bitcoin Core — Security advisories](https://bitcoincore.org/en/security-advisories/)
- [Bitcoin Core source — chainparams.cpp](https://raw.githubusercontent.com/bitcoin/bitcoin/master/src/kernel/chainparams.cpp)
- [Bitcoin Developer Glossary](https://developer.bitcoin.org/glossary.html)

## More in this section

- [Ethereum (ETH)](https://revain.org/projects/ethereum/)
- [XRP](https://revain.org/projects/ripple/)
- [Solana (SOL)](https://revain.org/projects/solana/)
- [All Crypto projects →](https://revain.org/projects/)

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Page updated: 2026-10-31

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Source: https://revain.org/projects/bitcoin/