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.