Introduction to Linux
Most modern operating systems provide an abstraction of the computer's hardware to the user and the programmer so that they don't have to worry about the details of hardware. For example, when a user changes disk drives in a computer or uses a floppy disk instead of a hard disk, they don't have to reformat their data or change the way they do their work.
The Linux abstractions involve users and groups, files and directories, programs and processes, and interfaces and sockets.
Users and groups allow separation between structures so that what can and cannot be done by whom under what circumstances are controllable.
Files and directories are used to store and retrieve information.
Programs and processes do all of the work. Any time you press a key, move a mouse, or push a button, the computer's side of the work involves programs and processes.
Interfaces and sockets are used to communicate with input and output devices, most often networks.
These structures are controlled by specific functions of the Linux operating system, and in many cases, these structures provide the means to observe and control what goes on in your computer.