Closed-source software (proprietary software) is software whose author owns all rights to use, modify, and copy it. Software products that do not meet the requirements for open-source software are generally categorized as closed-source software.
Restrictions of closed-source software
Creators of closed-source software products control access to the source code of their programs. This kind of product is typically delivered in the form of executable binaries and compiled libraries.
The end-user license agreement for a closed-source program normally contains provisions that prohibit its decompiling or any changes to the source code.
Lack of access to source code is a common, but not obligatory, feature of proprietary software. The code may be partially or wholly accessible in some cases, but its use without the author’s consent is unlawful.
The owner of proprietary software can:
- Make the source code available to everyone but place legal restrictions on its modification and use;
- Make the source code available to a limited group of individuals: auditors, government officers, key customers, etc.;
- Permit the use of a program’s source code under a certain agreement, free of charge or for a fee.
Software is proprietary by default under the laws of most countries. When creating a program, the author automatically receives all rights to its distribution, modification, and use, whereas waiving such rights requires documentation.
By contrast, a lot of open-source software, including some popular libraries, comes with a license that requires any products that use components of the software to be open-source as well. For example, such a restriction makes creating closed-source software based on a Linux core impossible.