CAPTCHAs: What They Are and How to Solve Them
Sep 02, 2010 · The entrant needs to type those characters before they can submit the form. In theory, computers can recognize text from images — but to do so reliably, they need a clean, crisp image. To make it difficult for computers to read the characters, CAPTCHAs are often distorted or placed on a confusing background pattern.
DA: 57 PA: 13 MOZ Rank: 40