Open source licenses are legal frameworks that dictate how software can be used, modified, and distributed, ensuring key freedoms for users and developers. Understanding the types of licenses is crucial: permissive licenses, like MIT, Apache 2.0, and BSD, impose minimal restrictions, while copyleft licenses, such as GPL and LGPL, require that derivative works remain open source. Choosing the appropriate license for your project involves balancing your goals, the level of freedom you wish to grant users, and ensuring compatibility with other licenses. Ensuring compliance with license terms is vital to avoid legal issues and maintain the integrity and success of open source projects. This knowledge is essential for anyone involved in software development, from hobbyists to enterprises, to navigate the open source landscape effectively.