What is Bitcoin? A clear definition of the decentralized currency, how it works, the 21 million cap, and why nations and companies hold it as a reserve asset.
Bitcoin is a decentralized digital currency and settlement network launched in January 2009 by the pseudonymous Satoshi Nakamoto. It allows value to be sent anywhere in the world, peer to peer, without banks, governments, or any central operator — secured instead by cryptography, a global network of nodes, and proof-of-work mining. Written with a capital B, "Bitcoin" usually refers to the network and protocol; lowercase "bitcoin" (or BTC) refers to the currency units themselves.
At its core, Bitcoin is a shared public ledger — the blockchain — that records every transaction ever made. Roughly every ten minutes, miners compete to bundle new transactions into a block by expending real-world energy on trillions of computations. The winner appends the block and collects newly issued bitcoin plus fees. Because rewriting history would require redoing that work against the entire network's combined power, confirmed transactions become practically irreversible. Ownership is controlled by private keys: whoever holds the key controls the coins, which is why self-custody and phrases like "not your keys, not your coins" carry so much weight in this industry.
Bitcoin's defining monetary property is absolute scarcity: the protocol caps supply at 21 million coins, enforced by every node on the network. New issuance halves roughly every four years in an event called the halving, meaning over 95% of all bitcoin has already been mined. No committee can vote to print more. This fixed supply is the foundation of the "digital gold" thesis and the primary reason governments and corporations now treat bitcoin as a reserve asset — the same logic explored in our guide to Strategic Bitcoin Reserves.
What began as a cypherpunk experiment now sits on sovereign and corporate balance sheets. The United States holds roughly 328,372 BTC in its Strategic Bitcoin Reserve, and total sovereign holdings tracked on our global reserve tracker exceed 650,000 BTC across countries from China to El Salvador — which made bitcoin legal tender in 2021. On the corporate side, Strategy alone holds over 843,000 BTC, and our public companies index tracks dozens more. The asset's journey from whitepaper to national reserve took less than two decades.
Bitcoin is not anonymous — it is pseudonymous, with every transaction publicly visible on-chain, which is precisely how analysts attribute government and corporate wallets. It is not "backed by nothing" in the sense critics mean; it is backed by energy expenditure, mathematics, and the largest distributed computing network ever assembled. And it is not primarily a payments rail anymore: while the Lightning Network handles fast small payments, Bitcoin's dominant use today is as a store of value and reserve asset. Volatility remains real — drawdowns of 50% or more have occurred in every market cycle — which is why position sizing matters even for sovereigns.
Every page on this site ultimately tracks one question: who holds bitcoin, and why? Understanding the asset itself — its fixed supply, its custody model, its verifiability — is the prerequisite for understanding why a US state legislature, a Japanese hotel company, and the IMF's most rebellious member state all arrived at the same balance-sheet decision. Bitcoin is the reserve; everything else on this site is the ledger of who's accumulating it.
Continue with Blockchain to understand the ledger beneath the currency, Halving for the supply schedule that enforces scarcity, Private Key for what ownership technically means, and Satoshi for the unit the protocol actually counts in. Then see who holds it: our public companies index ranks every major corporate treasury.