I hope I'm in the right forum, my question is out of curiosity and not due to an error. I notice that when I save images, sometimes Firefox has to download the image again, even though it displays just fine in the tab. Why is that? I tried the following experiment: I opened 2 tabs from a same domain, one recently loaded and one that was loaded an hour ago. I cut the internet connection. When I tried to save a random image, the tab that was loaded some minutes before saves the image alright, but the other tab doesn't save any image. I think it might have to do with cache settings, though I can't explain why an image that is loaded in a tab needs to be downloaded again (why not get it from the tab?). Where can I learn more about this behaviour? Thank you for your time and help! EDIT: going to "image information" in the context menu, sometimes it reports that the image I see in the page is not even in the cache(!). Where is it stored then?