The socket module is Python's standard interface for the transport layer, and it provides functions for interacting with TCP and UDP, as well as for looking up hostnames through DNS. In this section, we will introduce you to this module. We'll learn much more about this in Chapter 10, Programming with Sockets.

A socket is defined by the IP address of the machine, the port on which it listens, and the protocol it uses. The types and functions that are needed to work with sockets are in Python in the socket module.

Sockets are classified into stream sockets, socket.SOCK_STREAM, or datagram sockets, socket.SOCK_DGRAM, depending on whether the service uses TCP, which is connection oriented and reliable, or UDP, respectively.

The sockets can also be classified according to their family. We have Unix sockets, such as socket.AF_UNIX, that were created before the conception of the networks and are based on socket.AF_INET file, which are based on network connections and sockets related to connections with IPv6, such as socket.AF_INET6.