Permissive license
An open source license that lets anyone do almost anything with the code, including lock it inside a proprietary product, as long as the copyright notice comes along.
The opposite pole to copyleft. Where the GPL demands that changes ship under the same terms, a permissive license really asks for two things: keep the copyright line and license text, and don't sue the author when it breaks. The main families are MIT, BSD, ISC and Apache 2.0, the last of which also deals with patents.
The freedom cuts both ways. BSD code sits inside the operating systems of both macOS and the PlayStation, and neither vendor ever had to give a line back. Supporters call that the point; critics call it a subsidy for big companies. The permissive side has won anyway: MIT and Apache dominate new projects on GitHub.