A crypto address is where coins live. Every Bitcoin address, every Ethereum address, every Solana address is a string of characters — usually 26 to 62 long, usually starting with a predictable prefix — that is mathematically derived from a public key. When someone sends you Bitcoin, they send it to an address. When you check your balance, you are checking the balance associated with an address. The address is the entire on-chain identity of a wallet.
The format varies by chain. Bitcoin has had three generations of address format: legacy ones starting with 1, SegWit ones starting with 3, and the newer bech32 format starting with bc1. Ethereum addresses are 40 hexadecimal characters preceded by 0x. Solana uses base58 strings that look like 9WzDX.... Tron addresses start with T. None of them are easily memorable, which is why ENS (Ethereum Name Service) and similar projects exist to map human-readable names like vitalik.eth to real addresses.
Addresses are not private. The whole point of a public blockchain is that anyone can look up any address and see its full transaction history and current balance. Block explorers (Etherscan, Blockstream, Solscan) make this trivial. If you give someone your address, they can see everything that has ever happened to it.
Why You Have More Than One
Good wallet software generates a new address for every incoming transaction. This is a privacy practice: if you reuse the same address, anyone who knows it can link all of your transactions together and start building a picture of who you are and how you transact. Rotating addresses makes that correlation harder. Bitcoin wallets do this more aggressively than Ethereum wallets, partly because Ethereum’s account-based model makes multi-address management more annoying.
The other thing that complicates addresses is that they are chain-specific. A Bitcoin address cannot receive Ethereum. An Ethereum address cannot receive native Solana. Sending coins to an address on the wrong chain is one of the most common ways people lose money in crypto — if the target chain does not exist or cannot decode the address, the coins are usually gone. Always check the network before you hit send.