An address is where crypto goes. It looks like a random string of letters and numbers, but it works like an account number you can share freely. Bitcoin addresses start with 1, 3, or bc1. Ethereum addresses begin with 0x. Litecoin uses L or M. Send coins to the wrong format and they are gone. No bank to call. No reversal.

Every address comes from a public key, which comes from a private key. The private key is the one thing you never share. The address is derived through a one-way process: you can generate an address from a public key, but you cannot work backward. That is why posting your address online for donations is safe, while posting your private key empties your wallet in seconds.

Address formats by network

• Bitcoin Legacy — starts with 1, original format
• Bitcoin SegWit — starts with bc1, lower fees
• Ethereum — starts with 0x, used for ETH and ERC-20 tokens
• Litecoin — starts with L or M
• XRP — starts with r, may require a destination tag

QR codes make sharing easier and reduce typos. Copy-paste works too, but clipboard malware exists that swaps the address after you copy it. Always verify the first and last few characters before sending.