7. loeng Copyleft

 Copyleft

The concept of copyleft idea is programs have to be free. That does not connected with Marx ideas. As author of copyleft concept once said "To understand the concept, you should think of “free” as in “free speech,” not as in “free beer”". Program has to have open code. Everybody could see it, change and make difference in it. Or even make a new project based on that code. The only thing they can not do is to limit rights of the project. The rule of open code is permanent. That allow to all ideas fully unlock its potential.

Types of copyleft

• GNU General Public License

The most popular license. It does not allow to object become proprietary. It give rights to change the code or make copies.

• GNU Free Documentation License

License for objects of documentation type. It allow to change and spread the documentation commercially or not.

• GNU Lesser General Public License

Similar to GNU General Public License, but object licensed by Lesser License could be used in proprietaries programs.