Address

An address is the string a bitcoin sender pays to, encoding the conditions, usually a hash of a public key or script, under which the coins can later be spent. Modern native SegWit addresses use the bech32 format introduced in 2017 and start with bc1, while older formats begin with 1 or 3.

Why it matters

Addresses are the interface where user error meets irreversibility: a payment to a valid but wrong address cannot be recalled by anyone. The formats defend against this with built-in checksums, so a mistyped character produces an error rather than a loss, though they cannot defend against malware that swaps a correctly formed attacker address into the clipboard. Good practice treats addresses as single-use invoices rather than account numbers, because reuse links payments together on a public ledger.

Wallets automate this hygiene, deriving a fresh address for every receipt from a single seed, so the etiquette costs the user nothing.

How it works

A public key or script is hashed, and the hash is encoded with error-detecting structure: Base58Check for legacy addresses beginning with 1 or 3, bech32 for SegWit addresses beginning with bc1q, and bech32m for Taproot addresses beginning with bc1p. The address itself never appears on the blockchain; it decodes to the locking script that does, which is why one script can be re-expressed as exactly one address and vice versa.