Overview
Bitcoin is the first cryptocurrency. It was described in a 2008 paper by an anonymous author using the name Satoshi Nakamoto, and the network went live in January 2009. Satoshi disappeared in 2011, and nobody knows who they were.
Bitcoin’s idea is simple: digital money that no government, bank or company controls. Anyone can send it to anyone, anywhere, at any time, and nobody can print more of it than the rules allow. Seventeen years later it is by far the largest cryptocurrency, worth about $1.66 trillion, about 60% of the value of the entire crypto market.
How it works
Bitcoin runs on proof of work. Computers around the world, called miners, compete to solve a hard mathematical puzzle. The winner adds the next block of transactions to the blockchain, about every ten minutes, and earns newly created bitcoin plus the fees in that block.
Because rewriting the blockchain would require more computing power than all honest miners combined, Bitcoin’s transaction history is effectively impossible to change. Thousands of independent computers, called nodes, check every block against the rules, so miners can’t cheat either.
The main network handles only a few transactions per second, and fees rise when it is busy. For small, instant payments, users can use the Lightning Network, a layer on top of Bitcoin where payments cost a fraction of a cent.
The 21 million cap and halvings
| BTC at a glance | |
|---|---|
| Maximum supply | 21 million BTC |
| Already mined (Oct 2026) | about 20.1 million (96%) |
| Price (21 Oct 2026) | about $82,700 |
| All-time high | about $126,000 (October 2025) |
| Market cap | about $1.66 trillion (#1) |
There will only ever be 21 million bitcoin. About every four years, the reward miners get for each block is cut in half, in an event called the halving. The last halving was in April 2024, cutting the reward to 3.125 BTC per block, and the next is expected in 2028. The last bitcoin will be mined around the year 2140.
This fixed, predictable supply is why many people call Bitcoin “digital gold”: unlike dollars or euros, no central bank can create more of it.
From cypherpunks to Wall Street
Bitcoin has moved from the fringe to the mainstream:
- ETFs. US spot bitcoin ETFs have traded since January 2024 and quickly became some of the most successful ETF launches ever. BlackRock’s IBIT is the largest. Flows go both ways: on 19 October 2026, the ETFs took in about $527 million in a single day, after two weeks of outflows.
- Companies. Strategy (formerly MicroStrategy) holds about 848,000 BTC, around 4% of all bitcoin that will ever exist, and dozens of other listed companies hold BTC on their balance sheets.
- Governments. In March 2025, the US created a Strategic Bitcoin Reserve from bitcoin seized by the government. El Salvador made BTC legal tender in 2021, and several countries hold bitcoin.
In the third quarter of 2026, bitcoin rose about 43%, but it remains well below its October 2025 peak.
Security and reliability
Bitcoin has the strongest security record in crypto. Its network has not suffered a successful attack on its core rules, and it has run almost continuously since 2009. The last serious bugs, in 2010 and 2013, were fixed within hours. Its computing power is now enormous, which makes attacks extremely expensive.
Most bitcoin losses happen around Bitcoin, not in it: hacked exchanges, scams, lost passwords and seed phrases. Keeping your BTC on a reputable exchange or in a hardware wallet you control is the most important safety step.
Longer-term debates include:
- Miner income. As halvings shrink the block reward, miners will rely more on fees. Whether fees will be enough to keep the network secure decades from now is an open question.
- Quantum computers. Future quantum computers could in theory break the cryptography protecting some older bitcoin addresses. Developers are discussing upgrades, but nothing has been decided.
- Energy use. Mining consumes as much electricity as a mid-sized country, although a growing share comes from renewable or otherwise wasted energy.
Bitcoin vs. the competition
| Bitcoin | Ethereum | Gold | |
|---|---|---|---|
| Launched | 2009 | 2015 | Thousands of years ago |
| Supply | Fixed at 21 million | No cap, low issuance | Grows ~1–2% a year from mining |
| Main use | Store of value, payments | Apps, DeFi, stablecoins | Store of value, jewelry |
| Easy to send online | Yes | Yes | No |
| Volatility | High | Higher | Low |
Ethereum is a platform for apps, while Bitcoin focuses on being sound money. Compared with gold, bitcoin is easier to move, store and verify, but far more volatile and with a much shorter history.
Our verdict
Bitcoin is the foundation of crypto. Its fixed supply, its security record and its growing adoption by ETFs, companies and even governments make it the most established digital asset by a wide margin. For many investors, it is the first and largest crypto holding.
But “established” doesn’t mean safe. Bitcoin regularly falls 30–50% or more, as it has since its October 2025 high, and it can take years to recover. Invest only what you can afford to see drop sharply, think long term, and consider keeping your bitcoin in a wallet you control.
This review is for information only and is not financial advice.