Alphabet’s (NASDAQ:GOOG) Google has released a new version of the CAPTCHA test that will be less intrusive to internet users. The new Invisible reCAPTCHA feature is a free service is designed to protect sites and apps from spam and abuse The announcement is part of the news from this week’s Google Next ’17 conference in San Francisco.

CAPTCHA tests usually ask people to identify sequences of letters, numbers, or images to prove they’re human. The point of the test is to weed out fake bot traffic, which costs advertisers billions annually. Bots work endlessly to harvest email addresses, scrape sites, and reuse content without permission. However beneficial for advertisers, the tests have long been one of the most irritating parts of the internet for users.

Google is marketing the new version of the reCAPTCHA service as “tough on bots, easy on humans.” Google’s updated version works in the background to detect whether someone’s a human or a bot automatically. The company hasn’t supplied any details on how the security system works. All that Google will say is that the new test uses advanced risk analysis technology and machine learning to separate humans from bots.

While the system uses a broad range of cues to distinguish humans from bots, the company didn’t say what sort of behavior it considered suspicious. As sites switch over to invisible reCAPTCHA, most users won’t see CAPTCHAs at all. However, if you’re flagged as a suspicious user, you’ll still have to pass the usual challenges to prove you’re human. The new reCAPTCHA works on both desktop and mobile.

The company wrote on the reCAPTCHA Web site: “Since the launch of No CAPTCHA reCAPTCHA, millions of Internet users have been able to attest they are human with just a single click. Now we’re taking it a step further and making it invisible. Human users will be let through without seeing the ‘I’m not a robot’ checkbox, while suspicious ones and bots still have to solve the challenges.”

The reCAPTCHA platform is now the most widely used provider of CAPTCHA verification technology in the world, according to Google. Google bought reCAPTCHA in 2009 and said that it was working on a new version of the test back last year. The beta version launched last November. Google made it available for website developers as of last week.

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