Source software refers to the original, unmodified version of a program or application that is made available to users so they can study, modify and improve it. This type of software is typically released under open-source licenses which allow users to access its codebase, make changes and distribute their own versions. The idea behind source software is to promote transparency, collaboration and innovation in the development process by giving developers full control over the program's functionality and allowing them to contribute improvements back to the community.