A compiler is a computer program that accepts programs written in high level language and produces an object program.

Open-source software at present has a large market share in server software for Internet infrastructure. This market share means that there are many suppliers of consultancy services and instruction in open-source software in this area. Accordingly, there is some specific software based on open-source software. There are, for example, some e-commerce systems that use Apache as the server software.

Improvements in the usability of open source software do not necessarily mean that such software will displace proprietary software from the desktop; there are many other factors involved, e.g. inertia, support, legislation, legacy systems etc. However improved usability is a necessary condition for such a spread.

Possibility of savings:
Open-source software is not necessarily free, but in most cases is considerably cheaper than proprietary software. There may therefore be economic advantages for the public sector in using open-source software.

Security and quality:

“Programmer writes their code in a manner which is friendly for other programmers to modify and redistribute and use publicly”.  

Open source first evolved during the 1970s. Richard Stallman, an American software developer who believes that Sharing source-code and ideas are fundamental to freedom of speech, developed a ‘free’ version of the widely used ‘Unix’ operating system. The resulting ‘GNU’ program was released under a specially created General Public License (‘GNU GPL’). This was designed to ensure that the source-code would remain openly available to all. It was not intended to prevent commercial usage or distribution.

Open source software come along with GNU GPL (General Public License) license for use. Software under this license can be freely modified and redistributed. A license defines the rights and obligations that a licensor grants to a licensee. Open Source licenses grant licensees the right to copy, modify and redistribute source code (or content).

For software to be distributed as free software, the human-readable form of the program (the Source code) must be made available to the recipient along with a notice granting the above permissions.

OSS/FS is not "freeware"; freeware is usually defined as proprietary software given away without cost, and does not provide any right to examine, modify, or redistribute the source code. The most popular OSS/FS license is the General Public License (GPL); all software released under the GPL is OSS/FS

Open-source software (software with open source code) has become very popular in the last few years and is advancing at a speed unknown outside the world of IT.