timers
A small article on how you can implement multiple timers within Unix and Unix-like systems like Linux.
sockets, recv(), send(), accept(), listen()
Sockets programming is what is typically used to connect and communicate over a network.
pthreads, thread, mutex
Threads are a concept that allows programmers to execute multiple code paths in alternation. This allows, for instance, a program to execute an intensive calculation in one thread and keep another thread running for user input. This is an example of multitasking. POSIX threads are discussed.