Creative Commons licenses allow creators to choose how others can share and use their copyrighted work. There are six main Creative Commons licenses that differ in whether others can modify (derivative works), distribute commercially, or share derivatives under the same license. The most common licenses are Attribution (CC BY), which allows derivatives and commercial use as long as the original work is credited, and Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND), which only allows others to download and share the original work non-commercially.