The address is the identifier where a transaction is sent. The address is derived from a user’s public key. The public key is derived from the private key by asymmetric key cryptography. In Ethereum, the public key is 512 bits or 128 hexadecimal characters. The public key is hashed (i.e., uniquely represented) with a Keccak-256 algorithm, which transforms it into 256 bits or 64 hexadecimal characters. The last 40 hexadecimal characters are the public key. The public key usually carries the pre-fix “0x.” Also known as public address. Note: Keccak-256 does not follow the FIPS-202 based standard (a.k.a SHA-3).