Open Source is a method of developing software in which Source Code is openly and freely available to use. This is different than Propriety or Closed Source Software where Source Code is not available at all or not available to copy and modify. Open Source Software is generally developed publicly in collaborative manner. Linux, Apache, Mozilla Firefox are some of the popular Open Source Software.
Open Source Initiative (OSI)
OSI is a Non-Profit Corporation with prime objective of promoting, educating and formalizing Open Source Software Development. To be considered Open Source, Software must meet the criteria as defined in Open Source definition by Open Source Initiative. The criteria mainly include free redistribution of source code and license. OSI maintains a list of licenses that are considered Open Source. Most prominent of these licenses is GNU General Public License (GPL).
Here is a list of key Open Source Software Packages.
