6 types of Bitcoin addresses (in parentheses are the data they keep):
P2PKH 1... (a public key's hash)
P2SH 3... (a script's hash) (defined in BIP16)
SegWit (P2WPKH/P2WSH) nested in P2SH (defined in BIP141)
P2SH-P2WPKH 3... (a public key's hash)
P2SH-P2WSH 3... (a script's hash)
(these start with three because these addresses are meant to be ...