Creative Commons is an open licensing scheme in which creators retain the rights to their own work, but grant a licence to others to copy and distribute it in a certain manner and without the need to seek permission or pay royalties.
There are several types of licences. Some only allow material to be used as-is, while others allow users to modify the material for their own needs or to use it commercially.
The six main licences:
Understanding Creative Commons licences conditions
Watch the video Creative Commons: Finding Images.
For more information, visit these pages: