What is a wallet address?

A wallet address is a string of letters and numbers that identifies a destination on a blockchain. It works like a bank account number: you give it to someone so they can pay you. Sharing it does not put funds at risk, because spending requires the matching private key, a secret number that only the owner's wallet holds.

What does an address look like?

Each blockchain has its own format.

• Bitcoin addresses begin with 1, 3 or bc1.
• Ethereum addresses begin with 0x, followed by 40 characters made up of digits and the letters a to f.
• Solana addresses are strings of 32 to 44 letters and numbers with no fixed prefix.

Because addresses are long and easy to mistype, wallets show them as QR codes and offer a copy button. A single wallet can hold many addresses, and bitcoin wallets commonly produce a fresh one for each payment.

What happens if you send to the wrong network?

The same token often exists on several blockchains. A dollar stablecoin, for example, may be issued on Ethereum, Solana and various layer 2 networks, which are faster chains built on top of a main one. Ethereum and its compatible networks share one address format, so an address can be valid on several chains at once.

Problems arise when the sender picks a network the recipient does not use. If coins reach an exchange on a network it does not support, the exchange may be unable or unwilling to credit them, and some charge a fee to recover them. If the destination is a self-custody wallet on a compatible chain, the owner can usually reach the funds by adding that network, because the same key controls the address on each one. Coins that land at an address nobody holds the key for cannot be retrieved.

Some coins also require a short memo or tag alongside the address when depositing to an exchange.

What is address poisoning?

Address poisoning is a scam that exploits the habit of checking only the first and last few characters. A scammer generates an address that matches a real one at both ends, then sends the victim a tiny or zero-value transaction from it. The look-alike now sits in the victim's transaction history. If the victim later copies an address from that history, the payment goes to the scammer.

The guide to phishing and wallet drainers covers this and related tricks.

Is an address anonymous?

Not quite. An address carries no name, but every transaction it makes is public and permanent. Once an address is linked to a person, for instance through an exchange that checked their ID, their history can be followed. Can cryptocurrency be traced? explains how. The practical steps of a transfer are set out in how to send and receive crypto.