Definition: Applications that come with full Source Code that you can use are called Open Source.
There is an amazing amount of Open Source software on the Web and it makes an excellent way to learn by studying what others have written.
There is usually a copyright notice attached but that is usually just to prevent anyone taking an Open Source application and trying to sell it. Often it is licenced using the GPL or a variation of it.
Glossary:
A B C D E F G H I J K L M N O P Q R S T U V W X Y ZAlso Known As: Free Software
Examples:
Many programmers develop software for a living by day but in their spare time work on open source projects
