Networking concepts

Sockets are endpoints of communication.

They can reside on the same machine, on different machines on a local area network, or on extended networks such as the Internet.

A typical application consists of two programs, each having its own socket:

A server:

Listens on its socket for requests
Processes them
Returns a result (usually)

A client:

Makes requests to the server's socket
Listens for responses (if any)

the client requests and the server responds