Socket subroutines enable interprocess and network interprocess communications (IPC). Some socket routines are grouped together as the Socket Kernel Service subroutines.
Note: Do not call any Socket Kernel Service subroutines from kernel extensions.
The socket subroutines still maintained in the libc.a library are grouped together under the heading of Network Library Subroutines. Application programs can use both types of socket subroutines for IPC.