Different software generally have corresponding software license, the user must agree to software that use the software license under the condition of the use of software can legally. On the other hand, the license terms for specific software can also not contravene laws.
According to the different ways of permission, generally for several categories: software,
Exclusive software: such authorization usually don’t allow users to freely copy, modify or distribute research, the software. Violation of this license will usually have serious legal responsibility. The traditional commercial software companies will be adopted such as Microsoft Windows, and office software. Exclusive software source code is usually companies as the private property of strict protection.
Free software: such authorization coincided with exclusive software instead, giving users copy, modify, and distribute this research, and provide the right software source code for users to freely use only, give some other restrictions. With Linux, OpenOffice and as such Firefox software.
Sharing software: usually free and use the trial version, but in the use function or restrictions. Developers can encourage customers to pay the commercial version of complete function.