“Bitcoin” with a capital B commonly refers to the network or protocol. “bitcoin” with a lower-case b commonly refers to a unit recorded on that network. The distinction is a writing convention that makes a sentence easier to understand.
Bitcoin.org uses this convention in its vocabulary. It is not a rule enforced by the network, and changing a capital letter does not change an amount or a transaction.
Bitcoin: the network or concept
Bitcoin, with a capital B, is commonly used for the concept, protocol or entire network. For example: “The Bitcoin network records transactions.” In that sentence, Bitcoin is not an amount.
bitcoin: a unit of account
bitcoin, with a lower-case b, is commonly used for units of account. For example: “The record refers to two bitcoins.” BTC is a common abbreviation for one bitcoin.
Bitcoin.org also defines a satoshi as the smallest unit of bitcoin recorded on the blockchain. One bitcoin equals 100,000,000 satoshis. That relationship describes a unit of account; it does not state a price or value in pounds.
Why the distinction is useful
Without context, “Bitcoin” can mean a network, a protocol, an asset name or a quantity. Capitalisation can make it clearer which meaning is intended. It is especially helpful when explaining why a physical Bitcoin-themed object is different from an on-chain record.
For example, “A physical object does not itself control bitcoin on the Bitcoin network” uses both meanings. The physical item is not the network, and it does not automatically establish control of a recorded unit.
What this convention does not decide
Capitalisation does not prove ownership, authenticity, value, safety or legal rights. It is a language convention, not a method of checking a claim. A ticker symbol or a familiar name is not enough to establish what something is.
Read our physical Bitcoin coins guide for the collecting distinction, and use the crypto glossary for related terms such as blockchain and address.
Sources and scope
Source: Bitcoin.org vocabulary. This page explains language, not investment, tax or legal issues. Source check: 15 September 2026. To flag an error, contact The Coin Expert with the page and a source.