How it works: For URL-based searches, clicking a search engine opens it with the image URL pre-filled (where supported). For uploaded files, the image is shown — you'll need to drag it to the search engine, or use the "Upload" flow on the engine's site. TinEye and SauceNAO support direct URL search.
• Find the original source of an image (fact-checking, journalism)
• Identify a person from a profile photo (romance scam investigation)
• Find where else an image appears online (copyright, sockpuppet detection)
• Identify landmarks, products, or text in an image
• Verify if an "exclusive" photo has been used elsewhere before