What is open licensing?
It is first important to understand what a license is. See this box of the TCC Library Copyright guide to learn what a license is.
For open licenses, this information may be helpful:
Specifically, an open license exists as a way for the original creator to clearly inform others how their work can be used by granting permissions to share and adapt their work. A Public Domain license and the variety of open license permissions known as Creative Commons (CC) are the predominant standards for open licenses.
From this chapter of Getting Started with Pressbooks at TCC.