btcusd short appratunityThe unit of account of the bitcoin system is the bitcoin. It is most commonly represented with the symbol ₿ and the currency code BTC. However, the BTC code does not conform to ISO 4217 as BT is the country code of Bhutan, and ISO 4217 requires the first letter used in global commodities to be 'X'. XBT, a code that conforms to ISO 4217 though not officially part of it, is used by Bloomberg L.P.
No uniform capitalization convention exists; some sources use Bitcoin, capitalized, to refer to the technology and network, and bitcoin, lowercase, for the unit of account. The Cambridge Advanced Learner's Dictionary and the Oxford Advanced Learner's Dictionary use the capitalized and lowercase variants without distinction.
One bitcoin is divisible to eight decimal places. : ch. 5 Units for smaller amounts of bitcoin are the millibitcoin (mBTC), equal to 1⁄1000 bitcoin, and the satoshi (sat), representing 1⁄100000000 (one hundred millionth) bitcoin, the smallest amount possible. 100,000 satoshis are one mBTC.
Blockchain
Further information: Blockchain § Structure and design
As a decentralized system, bitcoin operates without a central authority or single administrator, so that anyone can create a new bitcoin address and transact without needing any approval. : ch. 1 This is accomplished through a specialized distributed ledger called a blockchain that records bitcoin transactions.
The blockchain is implemented as an ordered list of blocks. Each block contains a SHA-256 hash of the previous block, chaining them in chronological order. : ch. 7 The blockchain is maintained by a peer-to-peer network. : 215–219 Individual blocks, public addresses, and transactions within blocks are public information, and can be examined using a blockchain explorer.
Nodes validate and broadcast transactions, each maintaining a copy of the blockchain for ownership verification. A new block is created every 10 minutes on average, updating the blockchain across all nodes without central oversight. This process tracks bitcoin spending, ensuring each bitcoin is spent only once. Unlike a traditional ledger that tracks physical currency, bitcoins exist digitally as unspent outputs of transactions. : ch. 5
