This is something I only just looked at, but it works well. I installed the firefox plugin - it gives an extra option, when right-clicking any pic, to search for where it came from.
https://www.tineye.com
Reverse image search
Google also has a reverse image search as part of it's engine. Go to Image Search and click on the camera inside the right edge of the search box, then enter the image URL.
Tin Eye was around before Google Reverse Image Search but I've found the Google on to be more reliable. I guess they have a larger index of images.
Tin Eye was around before Google Reverse Image Search but I've found the Google on to be more reliable. I guess they have a larger index of images.