Linux® is an open-source operating system (OS). An operating system is software that directly manages a system's hardware and resources, like CPU, memory, and storage. The OS sits between applications and hardware and makes the connections between all of your software and the physical resources that do the work.
What is Linux used for today? Today, Linux systems are used throughout computing, from embedded systems to virtually all supercomputers, and have secured a place in server installations such as the popular LAMP application stack. The use of Linux distributions in home and enterprise desktops has been growing.
it is open source software (if you are interested in contributing to change in the code you can contribute it )
it is CLI (command line interface)
Linux History
After AT&T had dropped out of the Multics project, the Unix operating system was conceived and implemented by Ken Thompson and Dennis Ritchie (both of AT&T Bell Laboratories) in 1969 and first released in 1970. Later they rewrote it in a new programming language, C, to make it portable. The availability and portability of Unix caused it to be widely adopted, copied, and modified by academic institutions and businesses.
In 1977, the Berkeley Software Distribution (BSD) was developed by the Computer Systems Research Group (CSRG) from UC Berkeley, based on the 6th edition of Unix from AT&T. Since BSD contained Unix code that AT&T owned, AT&T filed a lawsuit (USL v. BSDi) in the early 1990s against the University of California. This strongly limited the development and adoption of BSD.[5][6]
In 1983, Richard Stallman started the GNU project to create a free UNIX-like operating system.[7] As part of this work, he wrote the GNU General Public License (GPL). By the early 1990s, there was almost enough available software to create a full operating system. However, the GNU kernel, called Hurd, failed to attract enough development effort, leaving GNU incomplete.[citation needed]
In 1985, Intel released the 80386, the first x86 microprocessor with a 32-bit instruction set and a memory management unit with paging.[8]
In 1986, Maurice J. Bach, of AT&T Bell Labs, published The Design of the UNIX Operating System.[9] This definitive description principally covered the System V Release 2 kernel, with some new features from Release 3 and BSD.
In 1987, MINIX, a Unix-like system intended for academic use, was released by Andrew S. Tanenbaum to exemplify the principles conveyed in his textbook, Operating Systems: Design and Implementation. While source code for the system was available, modification and redistribution were restricted. In addition, MINIX's 16-bit design was not well adapted to the 32-bit features of the increasingly cheap and popular Intel 386 architecture for personal computers. In the early nineties, a commercial UNIX operating system for Intel 386 PCs was too expensive for private users.[10]
These factors and the lack of a widely adopted, free kernel provided the impetus for Torvalds' starting his project. He has stated that if either the GNU Hurd or 386BSD kernels had been available at the time, he likely would not have written his own.
//copied from Wikipedia
Linux and Unix Linux can be freely distributed, as it is an Open Source OS. So anyone can get a copy of Linux from books, magazines, or on the internet also. For server versions, organizations typically pay distributors for a support contract, not the software. The major distributors are RED HAT, Mandrake, and SUSE. For server hardware, IBM, HP, and Dell are the major ones.
UNIX is costly as compared to Linux; the midrange UNIX servers are priced between $25,000 and $249,999 (including hardware). The major distributors are HP, IBM, and SUN. A high-end UNIX server can cost up to $500,000. According to IDC, and Gartner, IBM is the market leader in UNIX servers, HP is in 2nd position and SUN is in the third position.
Commercial UNIX is usually custom-written for each system, making the original cost quite high, whereas Linux has base packages also. In this respect, Linux is closer in its model to Windows than a commercial UNIX OS is. At the time of purchasing a UNIX server, users get a Vendor assistance plan on setting up and configuring the system. But with Linux, Vendor support must be purchased separately.