Open source software is software whose source code is freely available to the public and can be modified and redistributed by anyone without restraint or consequence. This is a very simple, watered-down version of the definition of open source. An official organization called the Open Source Initiative (http://opensource.org), founded in 1998 to organize the open source software movement in an official capacity, has provided a very clear and easy-to-understand definition of open source. During the course of writing this book, I obtained permission from the OSI Board to include it here.
Open source doesn't just mean access to the source code. The distribution terms of open source software must comply with the following criteria:
The license shall not restrict any party from selling or giving away the software as a component of an aggregate software distribution containing programs from several different sources. The license shall not require a royalty or other fee for such sale.
The program must include source code, and must allow distribution in source code as well as compiled form. Where some form of a product is not distributed with source code, there must be a well-publicized means of obtaining the source code for no more than a reasonable reproduction cost preferably, downloading via the Internet without charge. The source code must be the preferred form in which a programmer would modify the program. Deliberately obfuscated ...