When you send Monero to someone you only need one piece of information, and that is their Monero address. A raw Monero address is a set of 95 characters starting with a '4'. The Monero donation address, for instance, is 888tNkZrPN6JsEgekjMnABU4TBzc2Dt29EPAvkRxbANsAnjyPbb3iQ1YBRk1UXcdRsiKc9dhwMVgN5S9cQUiyoogDavup3H.
An integrated address is an address combined with an encrypted 64-bit payment ID. A raw integrated address is 106 characters long.
The address is actually the concatenation, in Base58 format, of the public spend key and the public view key, prefixed with the network byte (the number 18 for Monero) and suffixed with the first four bytes of the Keccac-256 hash of the whole string (used as a checksum).