What Is Bitcoin and How Does It Work?

Origin: the peer-to-peer electronic cash system

Bitcoin was proposed in a nine-page whitepaper published on 31 October 2008 by “Satoshi Nakamoto” — an identity that has never been revealed and may represent a single person or a group. The paper's opening sentence stated the problem precisely: “A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution.” Everything that followed was a technical blueprint for achieving exactly this.

The Bitcoin network went live on 3 January 2009. Satoshi mined the genesis block — Block 0 — which contained the now-famous embedded headline from that day's Times newspaper: “Chancellor on brink of second bailout for banks.”This message served as both a timestamp (proving the block could not have been mined before that date) and a statement of intent. For roughly a year, Satoshi was effectively the only developer and miner on the network, communicating with early collaborators via email and forum posts. By late 2010, Satoshi disappeared — handing the project over to its growing community of contributors, never to communicate publicly again.

The first documented real-world Bitcoin transaction occurred on 22 May 2010, now celebrated as “Bitcoin Pizza Day.” Developer Laszlo Hanyecz paid 10,000 BTC for two large pizzas. At Bitcoin's all-time high of $69,000 in November 2021, those pizzas would have been worth $690 million. At the April 2024 all-time high of $73,800, approximately $738 million. The story illustrates both how far Bitcoin has come and how early most of the world still is in understanding what they hold.

How Bitcoin transactions actually work

Most people think of Bitcoin wallets as containers that hold Bitcoin — like a physical wallet holds cash. This is a helpful mental model but technically inaccurate. Bitcoin does not “live” in wallets. Instead, the blockchain records a history of who received Bitcoin from whom, and your wallet contains the private keys that allow you to prove you have the right to spend specific unspent amounts from that history.

The technical term for these spendable amounts is UTXO — Unspent Transaction Output. When you receive 0.5 BTC, the network creates a UTXO of 0.5 BTC that can only be spent by whoever controls the corresponding private key. When you send 0.3 BTC to someone, you consume that 0.5 BTC UTXO and create two new UTXOs: 0.3 BTC for the recipient, and approximately 0.2 BTC back to yourself (minus transaction fees). Your “balance” is the sum of all UTXOs your private keys control.

When you initiate a transaction, your wallet software constructs a signed message proving your private key controls the UTXOs being spent and specifying the destination. This message is broadcast to the peer-to-peer network, validated by nodes, and queued in the mempool. Miners select transactions from the mempool (typically prioritising by fee per byte of block space), include them in a candidate block, mine the block, and broadcast it. Once included in a block and buried under six subsequent blocks (approximately one hour), the transaction is considered irreversible by most standards.

What mining actually does

Bitcoin mining is not a metaphor — it is the mechanism by which new Bitcoin is created and by which the network is secured. Miners are participants who dedicate specialised hardware (ASICs — Application-Specific Integrated Circuits, designed exclusively for Bitcoin hashing) to compete for the right to add the next block to the blockchain.

The competition works as follows: miners take the current candidate block (containing transactions from the mempool, a timestamp, and a reference to the previous block's hash), add a random number called the nonce, and hash the result using Bitcoin's SHA-256 algorithm. If the resulting hash is below the current difficulty target (which appears as the hash beginning with a specific number of zeros), they have mined a valid block. If not, they increment the nonce and try again. Modern ASIC miners perform hundreds of trillions of these calculations per second. The entire Bitcoin network collectively performs over 500 exahashes per second — more than the combined processing power of the world's largest supercomputers by a factor of millions.

The first miner to find a valid block broadcasts it to the network, receives the block reward (currently 3.125 BTC after the April 2024 halving), and all the transaction fees from the included transactions. Other miners validate the block and begin working on the next one. This process occurs roughly every 10 minutes, adjusted automatically by Bitcoin's difficulty algorithm to maintain that cadence regardless of how much total mining power is participating.

The halving — Bitcoin's programmed scarcity

Every 210,000 blocks (approximately four years), the block reward halves. This event is called the halving, and it is one of Bitcoin's most important design features. The halving was written into Bitcoin's code from day one — it is not a policy decision that can be changed by any authority, but a rule enforced by every node in the network.

The halving mechanics create an asymptotic approach to the 21 million cap. The first 210,000 blocks (2009–2012) produced 50 BTC each, distributing 10.5 million BTC — exactly half of the total supply. The next era distributed 25% of the total. Each halving adds exactly half of what the previous era added. By the 2024 halving, over 93% of all Bitcoin that will ever exist had already been mined. By 2032, over 98%. The final Bitcoin is estimated to be mined around the year 2140, at which point miners will rely entirely on transaction fees for revenue.

Historical halvings and price context

The 2012 halving (50 BTC → 25 BTC) occurred when Bitcoin traded around $11. Within 12 months, Bitcoin reached $1,163 — a 105x move from the halving price. The 2016 halving (25 BTC → 12.5 BTC) occurred at roughly $650. Bitcoin peaked at $19,783 in December 2017 — a 30x move. The 2020 halving (12.5 BTC → 6.25 BTC) occurred at approximately $8,600. Bitcoin peaked at $69,000 in November 2021 — an 8x move. The pattern of post-halving bull markets is documented but not guaranteed: markets adapt, and each cycle occurs in a different macro environment with different institutional participation. The 2024 halving occurred during a period of Bitcoin spot ETF approval in the US — a different context entirely from previous cycles.

The digital gold thesis — why it has resonated

Gold has functioned as a store of value and monetary metal for roughly 5,000 years. Its monetary properties — scarcity, durability, divisibility, portability, and fungibility — made it the foundation of global monetary systems until the 20th century. The gold standard was abandoned in stages, culminating in Nixon's 1971 decision to end the convertibility of dollars to gold, after which all major currencies became fiat — backed only by government decree and institutional trust.

Bitcoin's proponents argue it improves on gold in several critical dimensions. Bitcoin is more easily verifiable: the authenticity of a gold bar requires physical testing, but a Bitcoin balance can be cryptographically verified by anyone running a node. Bitcoin is more portable: moving $1 million in gold across a border requires physical transport, security, and customs compliance; moving $1 million in Bitcoin requires a transaction broadcast from a phone. Bitcoin is more divisible: it can be transacted in units of one hundred millionth (called satoshis or “sats”), enabling micropayments impossible with gold. And Bitcoin's supply schedule is more predictable: gold's annual supply growth (roughly 1.5%) depends on future mining discoveries; Bitcoin's is mathematically fixed.

These properties attracted institutional interest that transformed Bitcoin's investor base. MicroStrategy began accumulating Bitcoin in August 2020 and held over 200,000 BTC by 2024 — treating it as a primary treasury reserve asset. Tesla bought $1.5 billion of Bitcoin in 2021. The approval of spot Bitcoin ETFs by the SEC in January 2024 — including products from BlackRock, Fidelity, and Invesco — represented the formal integration of Bitcoin into traditional finance, with over $10 billion flowing into these products in the first two months of trading.

Bitcoin's genuine limitations

Intellectual honesty requires acknowledging Bitcoin's real limitations, not just its strengths. Transaction throughput is the most significant: the base layer processes approximately 7 transactions per second, compared to Visa's 24,000. Bitcoin was not designed for high throughput — it was optimised for security and decentralisation. The Lightning Network (a Layer 2 protocol for near-instant micropayments) partially addresses this, but Lightning adoption has been slow and the user experience remains technically complex for ordinary users.

Energy consumption is genuinely substantial. Bitcoin mining consumes roughly 140 TWh per year — comparable to Argentina's national electricity consumption. Proponents argue this energy expenditure is the cost of a decentralised, censorship-resistant monetary system that secures $1+ trillion in assets, and that an increasing proportion comes from renewable sources. Critics argue the environmental cost is not justified by the benefits, particularly when compared to Proof of Stake systems that achieve similar security with 99.9% less energy. This debate has no definitive resolution — it is a question of values and priorities, not pure fact.

Volatility is the limitation most relevant to Bitcoin's use as money. A currency that can fall 50% in three months makes pricing goods, writing contracts, and planning financially extremely difficult. El Salvador's experience as a Bitcoin legal tender country demonstrated this in practice: most citizens continued using dollars for daily transactions even after Bitcoin became legal tender. Bitcoin may store value over multi-year periods while remaining unsuitable as a day-to-day medium of exchange until volatility decreases substantially — which historically requires much larger market capitalisation and widespread adoption.