Bitcoin is a decentralized digital currency that allows peer-to-peer transactions without banks or intermediaries. It runs on a public ledger called a blockchain, secured by cryptographic proof-of-work mining, with a hard supply cap of 21 million coins.
What Is Bitcoin?
3 min read
The short version
Think of Bitcoin as digital cash that nobody controls. Like sending an email instead of a physical letter, Bitcoin lets you send money directly to anyone in the world without asking a bank for permission. The network itself, thousands of computers worldwide, verifies every transaction.
How It Works
Bitcoin works through a network of nodes that each maintain a copy of the blockchain, a chronological chain of transaction blocks. When you send Bitcoin, your transaction is broadcast to the network. Miners compete to bundle pending transactions into a new block by solving a computationally intensive puzzle (proof of work). The first miner to solve it adds the block to the chain and earns a block reward (currently 3.125 BTC after the 2024 halving). Each block references the previous block's hash, making the chain tamper-evident. Your Bitcoin isn't stored in a file, it exists as unspent transaction outputs (UTXOs) recorded on the blockchain, controlled by your private key.
Sending 0.05 BTC to a friend
Alice wants to send 0.05 BTC to Bob. She opens her wallet, enters Bob's Bitcoin address (bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4), and sets a fee of 4,000 satoshis (about $2.40 at $60,000/BTC). Her wallet creates a transaction referencing her previous unspent outputs, signs it with her private key, and broadcasts it. Within 10 seconds the transaction appears in mempools worldwide. After approximately 10 minutes, a miner includes it in a block. After 3 confirmations (~30 minutes), Bob's wallet shows the 0.05 BTC as fully confirmed. You can verify any Bitcoin transaction like this on blockstream.info or mempool.space by searching the transaction ID.
What People Get Wrong
Bitcoin is anonymous
Bitcoin is pseudonymous, all transactions are publicly visible on the blockchain. Addresses can often be linked to real identities through exchanges, IP analysis, or spending patterns.
Bitcoin has no intrinsic value
Value is subjective. Bitcoin derives utility from its censorship resistance, fixed supply, portability, and the energy securing its network, properties no other asset combines identically.
Bitcoin wastes energy
Bitcoin mining consumes energy, but increasingly from stranded or renewable sources. The energy secures a $1T+ network, whether that is "waste" depends on whether you value the network's properties.
Bitcoin transactions are instant
On-chain transactions require block confirmations (~10 min each). Layer 2 solutions like the Lightning Network enable near-instant payments for smaller amounts.
Keep Reading
Sources & Further Reading
- Bitcoin Whitepaper (PDF)
The original 9-page paper by Satoshi Nakamoto describing how Bitcoin works
- Bitcoin.org Developer Guide
Official technical documentation for Bitcoin protocol and development
- Mempool.space
Live Bitcoin mempool visualizer, fee estimator, and block explorer
Questions People Also Ask
- Who created Bitcoin?
- Bitcoin was created by the pseudonymous Satoshi Nakamoto, who published the whitepaper on October 31, 2008, and launched the network on January 3, 2009 (the genesis block timestamp). Satoshi mined an estimated 1 million BTC in the early blocks but has never moved any of it. They disappeared from public communication in April 2011. Their identity remains unknown.
- Can Bitcoin be hacked?
- The Bitcoin protocol itself has never been hacked in over 15 years of continuous operation. The network is secured by approximately 600 EH/s of hash power (as of 2024), making a 51% attack cost an estimated $10+ billion in hardware alone. Thefts occur when individuals or exchanges fail to secure their private keys, a custody problem, not a protocol vulnerability.
- How many Bitcoin are left to mine?
- As of 2024, approximately 19.7 million of the 21 million total Bitcoin have been mined. About 1.3 million remain to be mined over the next 116 years. The block reward is currently 3.125 BTC (since the April 2024 halving at block 840,000). The next halving occurs at block 1,050,000, expected around March 2028.
- Is Bitcoin legal?
- Bitcoin is legal to buy, hold, and sell in the US, EU, UK, Japan, Australia, Canada, and most countries worldwide. El Salvador and the Central African Republic have adopted it as legal tender. China banned crypto trading in 2021 but holding is not criminalized. A few countries (Bangladesh, Nepal, some Gulf states) have outright bans. Always verify your specific jurisdiction at your national financial regulator website.