Linux is one of popular version of UNIX operating System. It is open source as its source code is freely available. It is free to use. Linux was designed considering UNIX compatibility. Basic Features Following are some of the important features of Linux Operating System. Portable - Portability means softwares can works on different types of hardwares in same way.Linux kernel and application programs supports their installation on any kind of hardware platform. Open Source - Linux source code is freely available and it is community based development project. Multiple teams works in collaboration to enhance the capability of Linux operating system and it is continuously evolving. Multi-User - Linux is a multiuser system means multiple users can access system resources like memory/ ram/ application programs at same time. Multiprogramming - Linux is a multiprogramming system means multiple applications can run at same time. Hierarchical File System - Linux provides a standard file structure in which system files/ user files are arranged. Security - Linux provides user security using authentication features like password protection/ controlled access to specific files/ encryption of data.