AddressFamily's are types of addresses for networking.

see bind(2), socket(2)

some examples: | ProtocolFamily | AddressFamily | ManPages? | Protocol Type | Protocols | Description |v PF_INET |v AF_INET |v ip(7) | SOCK_STREAM | TCP |v IPv4 sockets. | SOCK_DGRAM | UDP |v PF_INET6 |v AF_INET6 |v | SOCK_STREAM | TCPv6 |v IPv6 sockets. | SOCK_DGRAM | UDPv6 |v PF_UNIX, PF_LOCAL |v AF_UNIX, AF_LOCAL |v unix(7) | SOCK_STREAM | - |v Unix domain sockets | SOCK_DGRAM | - | PF_APPLETALK | AF_APPLETALK | ddp(7) | ? | ? | Appletalk sockets | PF_X25 | - | x25(7) | ? | ? | ITU-T X.25 / ISO-8208 protocol | PF_IPX | - | - | ? | ? | IPX? - Novel protocols | PF_AX25 | - | - | ? | ? | Amateur radio X.25 protocol | PF_ATMPVC | - | - | ? | ? | Access to raw ATM PVC's | PF_PACKET | AF_PACKET | packet(7) | ? | ? | Lowlevel packet interface | PF_NETLINK | AF_NETLINK | netlink(7) | ? | ? | Kernel user interface device