: you give permission for others to download your resource for free and also to create new works based on it. They’ll have to give you credit for your work using the same license, and they can’t sell your work, or their works based on it. This is the most popular choice.
: you give permission for others to download your resource for free and also to create new works based on it without restriction, as long as they give you credit. As a result, others could sell a resource adapted from your work and make money from it.
: you give permission for others to download your resource for free and share it, but they can’t create new works based on it even if they give you credit.