I needed an image of a robot for a presentation, and I wanted an image with a free (e.g. creative commons) license. I searched in Google images "robot free", but got mostly royalty-free images (i.e. after you buy the image, you are free to use it).
I remember that once it was possible to search in Google for images with a public-domain or creative-commmons license, but now I cannot find it. Where is it?