Proprietary software or closed source software is computer software licensed under exclusive legal right of the copyright holder with the intent that the licensee is given the right to use the software only under certain conditions, and restricted from other uses, such as modification, sharing, studying, redistribution, or reverse engineering.[1][2] Usually the source code of proprietary software is not made available.
Complementary terms include free software,[2][3] licensed by the owner under more permissive terms, and public domain software, which is not subject to copyright and can be used for any purpose. Proponents of free and open source software use proprietary or non-free to describe software that is not free or open source.[4][5]
A related, but distinct categorization in the software industry is commercial software which refers to software produced for sale, but without meaning it is closed source.