1. If you took it
  2. If it’s directly related to a movie/music release/tv show/any other type of popular media (such as screencaps of 30 Rock eps, images of Zach Quinto or posters of recent films)
  3. If it’s from 4chan (trust us, we can tell)

IN EVERY OTHER CIRCUMSTANCE, CREDIT MUST BE GIVEN TO THE SOURCE* OR PHOTOGRAPHER. NO EXCEPTIONS.

Reblog if you believe tumblr should have better options to prevent actions that are not only degrading to the original creator of the image but also to the internet community as a whole.

*A source does not mean a link to the static image. It means a link to at least the originating page.