Explain the philosophy of Open Source. Enlist any four criteria that qualifies a program to be Open source software.

Open source is a philosophy that promotes the free access and distribution of an end product, usually software or a program. It may extend to the implementation and design of other products. Such software, generally, gives users the freedom to run the software for any purpose, to use and modify the software, and to redistribute copies of the original and modified versions to others. These permissions are enforced through an open source licence.

Four criteria that qualify a program to be Open source software are:

1. Free Redistribution — There shall be no restriction on the sale or distribution of the software, partial or whole, and such a sale shall be free of any royalty charges or any other fee.
2. Source Code — The distributed program must include the source code as well as its compiled form. In cases where it is not included, the source code must be easily accessible from public sources on the Internet.
3. Derived Works — The licence must allow modifications and derived works. It must allow them to be distributed under the same terms as the licence of the original software.
4. No Discrimination against Persons or Groups — The licence must not discriminate against any person or group of persons.