Block Explorer

A block explorer is a website that lets anyone search a blockchain and read its public data: transactions, addresses, blocks, fees and smart contract code. Because blockchains are transparent, you can paste a transaction hash and see whether it confirmed, how much gas it cost and which addresses were involved, without an account or permission. Explorers are the standard way to check that a withdrawal from an exchange actually went through, to inspect a token contract before interacting with it, and to review which approvals an address has granted. Keep in mind that explorers show what is on-chain, not who owns an address, and that labels shown for addresses are provided by the explorer, not proven by the protocol.