Open source refers to software where the source code is open to the public and can be reused, modified, and even redistributed by anyone. It differs from closed source software, which contains proprietary code and can only be used in specific ways governed by a license. Open source software is developed in a collaborative fashion, typically with input from a variety of sources, and is often released for free. This helps to promote innovation, creativity, and independence by allowing developers to customize the software to suit their specific needs and to contribute to the development of the software for the benefit of the public.