Open or free licenses are a legal mechanism that has been designed so that authors or rights holders who want to allow free use of their works can do so with the guarantees of a legal text compatible with copyright laws.

They are licenses that allow, to the generality of people, to use the works (with certain conditions) without having to sign express agreements with the holders of the copyright.

It is very important that the author who decides not to reserve all rights, and thus allow the free use of his work under certain conditions, is well aware of the license he chooses at the time of registration:

• Here you can read more about the concept itself and about the most commonly used types of licenses: Creative Commons.
• Other recommended reading: What is Copyright © and Copyleft (open licenses)?