Exchange on Ethereum

An Ethereum address is 0x plus 40 hex characters, 42 in total. Upper and lower case letters in it act as a checksum (EIP-55): an all-lowercase address is valid too, and with mixed case a wallet will catch a typo. Wallets can resolve ENS names like name.eth into an address, but exchanges and many services expect the 0x address itself.

Tokens on Ethereum follow the ERC20 standard. BNB Smart Chain, Arbitrum, Base, Optimism, Polygon and other EVM networks use the same address format: one key gives one address on all of them, while a token on each network is a separate asset. If you mix up the network when sending to your own wallet, the funds can be reached with the same key on the other network; if you send to an exchange, only its support can return them, and not always. Coins from other blockchains exist on Ethereum as wrapped or bridged ERC20 tokens, and they cannot be sent straight to an address on the coin's home network.

Fees (gas) on Ethereum are paid only in ETH, token transfers included. A plain ETH transfer costs 21,000 gas units, an ERC20 transfer more, and the price per gas unit moves with network load. A wallet holding USDT or another token but no ETH cannot send the tokens.

An Ethereum slot lasts 12 seconds, and a transaction usually lands in a block within one or two slots. It becomes final (finalized) after two epochs, about 13 minutes; exchanges often credit earlier, after their own number of confirmations. Ethereum has no memo: exchanges give each client a separate address.

Common mistakes are sending tokens to the token's own contract address (they usually stay there for good) and copying an address from the transaction history, where scammers plant lookalikes with the same first and last characters. Check the whole address.