Open source is source code that is made freely available to be modified by the public as well as can be redistributed. It is a decentralized software development model that encourage people for open collaboration. It began as a response to the limitation and weakness of the "closed source" proprietary code.
Generally, open source refers to a computer program whose source code is available to the public for use or modification from its initial design. Code is released under the terms of a software license. Depending on the license terms, people can download, modify, and publish their version (fork) back to the community.Open source software is usually a free software product, where people have access to the source code. They can enhance the program’s performance, add some features, and fix errors. Some examples of such software are LibreOffice, Firefox, and VLC Media Player.
Collaboration between different peoples can bring new ideas that can be implemented on it leading to better software.
It is secure to use because anyone can look what's going behind the scenes unlike proprietary softwares.
Since the code can be modified by anyone, anyone can customize it to their own liking.
Usually free to use.
You actually can own your software instead of renting it.
Commercialization is difficult to achieve.
Fragmentation of software if a person doesn't like what the original community is doing. ( This can also be an advantage of Open Source, depending upon people's perspective. )
There is always the possibility that the developers of a program lose interest in working further on the software or just move on to another project.
Unlike proprietary softwares where you can phone or email them for instant tech support open source doesn't have a proper tech support medium.