Final answer:
Open source software is a type of program that allows users to freely use, share, and modify its source code. It's typically under licenses like Creative Commons Attribution, which require crediting the original source. The OER LibreTexts Project is an example of a platform providing open source texts.
Step-by-step explanation:
Open source software refers to programs whose source code is made publicly available. This means that anyone can use, share, or modify the software freely. A critical aspect of open source software is its license which often allows users to legally remix, tweak, and build upon the work.
An example of such licensing is the Creative Commons Attribution license, which not only permits but encourages modification, as long as the original creator is credited, and the new creation is licensed under identical terms. Platforms like the Open Education Resource (OER) LibreTexts Project provide a vast range of open-access texts which users can read, print, and in most cases, also modify according to the specific license provided for each book.