CC BY: Only attribution needed

CC BY is the simplest Creative Commons licence: you can copy, distribute, remix, and build on the work, even for commercial purposes, as long as you give appropriate credit to the original creator. The key contrast is with CC BY-SA, which adds a share-alike condition meaning any derivative must use the same licence, or CC BY-NC, which bans commercial use. In an exam, if you see a scenario where someone uses a photo for profit and only credits the photographer, that is fine under CC BY but would violate CC BY-NC.

To avoid traps, remember that BY alone never restricts commercial use or requires derivatives to be shared under the same terms. A quick elimination trick: if the question mentions "non-commercial" or "share-alike", the licence cannot be plain CC BY. Also, note that attribution must be reasonable—include the creator's name, title, source, and licence link if possible. In multiple-choice questions, watch for options that list CC BY but add extra restrictions; those are wrong.

A compact way to test yourself: imagine you find a CC BY image and want to sell it on a T-shirt. You can, as long as you credit the photographer. If the licence were CC BY-NC, you could not. This one contrast—commercial use allowed versus not—is the fastest way to distinguish CC BY from its cousins.