When someone creates something (like a picture or book), they can choose to make that work "open". This means that other people are allowed to copy it and change it if they want. Something that is open content may be free of charge, but it does not have to be. The Simple English Wikipedia is open content. So are other Wikipedias. If a person changes open content or makes new open content, everyone can give it to anyone else, or even sell it. It is never needed to ask permission to do this, because the people who wrote the text already gave their permission when they clicked the Save button.