A term used to define what is basically free software. Open source software actually has the source code of the program available to anyone. That allows individual programmers to modify the software to meet their needs and to improve the original product. Open source software is also free for individuals to download and run – unlike something like MS Office where you must pay to use it, you can use open source software for free.
Common open source software programs are WordPress and Drupal (for websites), Audacity (for sound editing), and Zotero (for bibliographies). Another major line of open source software is the open source operating system Linux and its various user-friendly forms, such as Ubuntu.
Open source programs typically are less beautiful than the proprietary counterparts but have all the same features. Documentation can be as good as or better than proprietary software.