Bitcoin

A Bitcoin (₿ or BTC) is a digital currency and asset that exists entirely on the blockchain, unsecured by government backing or central authority. Created in 2009 by pseudonymous inventor Satoshi Nakamoto, Bitcoin operates on a peer-to-peer network and is secured by proof-of-work mining.

History and purpose

Bitcoin emerged from decades of failed attempts to create digital cash. The white paper “Bitcoin: A Peer-to-Peer Electronic Cash System,” published in 2008 under the pseudonym Satoshi Nakamoto, proposed a solution to the “double-spend problem” — how to prevent someone from spending the same digital coin twice without a central authority to verify transactions.

The network went live on 3 January 2009, with Nakamoto mining the first block (called the genesis block). Bitcoin’s stated purpose was to enable “peer-to-peer electronic cash” that could move across borders without intermediaries. Over time, as adoption grew and transaction volumes increased, the network evolved into something closer to “digital gold” — a store of value rather than a medium of exchange for everyday commerce.

How Bitcoin works

Bitcoin is a blockchain where each block contains cryptographically verified transactions. Every ten minutes (on average), the network produces a new block and adds it to the chain. Miners — operators of specialised computers — compete to solve a difficult mathematical puzzle; the first to solve it gets to propose the next block and receives a reward of newly minted Bitcoin plus transaction fees.

This mechanism, called proof-of-work, secures the network without a central authority. An attacker trying to rewrite history would have to control more than 50% of the total hash rate, making Bitcoin increasingly secure as more miners join.

Supply and the halving

Unlike fiat currencies, which central banks can print without limit, Bitcoin has an absolute maximum supply of 21 million coins. This scarcity is programmed into the protocol itself. Every four years (or more precisely, every 210,000 blocks), the reward miners receive for adding a block is halved. This event, called the Bitcoin halving, will continue until around 2140, when the last Bitcoin is mined and the supply is complete.

Bitcoin’s hard cap is often cited as one reason investors view it as “digital gold” — a scarce, inelastic asset that cannot be debased through inflation. However, this fixed supply also means Bitcoin cannot be deployed as a monetary policy tool during crises, as fiat currencies can be.

Major properties

Immutability. Once a transaction is confirmed in a block and buried under subsequent blocks, it becomes prohibitively expensive to reverse. This makes Bitcoin highly resistant to fraud but also means there is no “undo” button if you send funds to the wrong address.

Pseudonymity, not anonymity. Bitcoin transactions are published on a public ledger and can be traced if someone knows which address you control. This differs from Monero, which uses cryptographic privacy features to obscure amounts and parties.

Slow finality. A transaction is typically considered final after six blocks (about one hour) have accumulated. For comparison, credit cards settle in seconds. This makes Bitcoin impractical for everyday retail purchases.

No reversals. Bitcoin has no mechanism for chargebacks or refunds. If you are defrauded, the funds are gone permanently unless the recipient chooses to return them.

The Bitcoin network today

As of 2025, Bitcoin is the largest cryptocurrency by market capitalisation, with thousands of independent miners and nodes securing the network globally. The vast majority of Bitcoin trading occurs on centralised exchanges, though peer-to-peer trading is also common.

Bitcoin is held both by speculators betting on price appreciation and by long-term investors who view it as a hedge against currency debasement. Some countries and institutions have adopted Bitcoin as part of their treasuries, while others have banned or heavily restricted its use.

Technical limitations and debates

The original Bitcoin protocol processes roughly seven transactions per second. This is far slower than traditional payment systems and has sparked ongoing debate about scaling solutions. Some advocates propose layer-2 systems that batch transactions off-chain; others support increasing the block size; still others argue Bitcoin should remain a settlement layer for large transfers rather than replace everyday payments.

Mining’s energy consumption is another focal point. Bitcoin’s proof-of-work mechanism requires enormous amounts of electricity. Defenders argue the energy expenditure buys genuine security and immutability; critics contend that alternative consensus mechanisms are more efficient.

See also