Google image search allows you to search an image’s URL (or upload an image) to find where that image appears online and to find similar images.
Beware that similar images may be visually similar but not necessarily related, as in this example:
Photographers can use image search to see if their photo is being used on other websites. Social media editors can use it to make sure a user-submitted photo of a news event isn’t actually an old image, and anyone can use it to find out where an image originated. (Click on the links in that previous paragraph for examples and for information about Tineye and other ways to do reverse image searches.)
How to do it:
Go to images.google.com and click the camera icon in the search box. Paste the URL of an image on the web, or upload an image from your computer.