What is a process?
An instance of a running program is called a process. Every time you run a shell command, a program is run and a process is created for it. Each process in Linux has a process id (PID) and it is associated with a particular user and group account.
Linux is a multitasking operating system, which means that multiple programs can be running at the same time (processes are also known as tasks). Each process has the illusion that it is the only process on the computer. The tasks share common processing resources (like CPU and memory).
To be a good Linux administrator, you need to be familiar with a wide range of commands that enable you to list, identify or delete a process. In the next lessons we will describe such commands.