One click tells Google you're not a robot

[Priyanka]

Google announced that many of its "Captchas" -- the squiggled text tests designed to weed out automated spambots -- will be reduced to nothing more than a single checkbox next to the statement "I'm not a robot." No more typing in distorted words or numbers; Google says it can, in many cases, tell the difference between a person or an automated program simply by tracking clues that don't involve any user interaction. The giveaways that separate man and machine can be as subtle as how he or she (or it) moves a mouse in the moments before that single click.

[nitish]

"Captchas" are necessary nowadays as they help in reducing spams.