If you’ve shopped online you have probably used CAPTCHA. CAPTCHA is a program that identifies its user as human or computer. CAPTCHAs prevent abuse from “bots,” or automated programs that generate spam. No computer program can read distorted text as well as humans can, so bots cannot navigate sites protected by CAPTCHAs.
About 200 million CAPTCHAs are solved around the world every day. Each take approximately ten seconds to complete, which isn’t a lot of time, but when added up these little puzzles consume more than 150,000 hours of work each day.
To archive human knowledge and to make information more accessible, multiple projects are currently utilizing CAPTCHAs to digitize books that were published before the computer age.
Books are scanned and transformed into text using Optical Character Recognition (OCR) software but it is not perfect. Many of the 200 million CAPTCHAs solved by humans each day are words OCR could not correctly identify. Therefore, you are actually part of a team that is archiving human knowledge.
If you run a website that suffers from problems with spam, you can put CAPTCHA on your site.