FOSS – Free and Open Source Software
Open source software means the software which is free to use .There are 4 types of freedom in software in FOSS,
* The freedom to run the program, for any purpose (freedom 0).
* The freedom to study how the program works, and change it to make it do what you wish (freedom 1). Access to the source code is a precondition for this.
* The freedom to redistribute copies so you can help your neighbor (freedom 2).
* The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.