Twitter began testing its “tailored audiences” ad retargeting back in the summer and has now announced the feature’s global availability.

“With tailored audiences you can reach users on Twitter who have shown interest in your brand or your category even away from Twitter,” explains Twitter revenue product manager Abhishek Shrivastava. “Let’s say a hotel brand wants to advertise a promotion on Twitter and they’d prefer to show their ad to travel enthusiasts who have recently visited their website. To get the special offer to those people who are also on Twitter, the hotel brand may share with us browser-related information (browser cookie ID) through an ads partner. We can then match that information to Twitter accounts in order to show the matched users a Promoted Tweet with the travel deal. The end result is a highly relevant and useful message for the user.”

“Targeting recent visitors to your website is just one way to use tailored audiences,” says Shrivastava. “We believe there are many other possibilities. Think of it as the way to define your own groups of existing and target customers, and connect with them on Twitter.”

Advertisers will still get the same reports as usual, showing how many saw and clicked on an ad.

If you’re concerned about privacy, you can uncheck the box next to “promoted content” in your privacy settings, and Twitter won’t match your account to info shared by partners for tailoring ads. If you have Do Not Track enabled, Twitter won’t use cookies.

The company says results from early testing have been impressive. Brands include HubSpot, Krossover, New Relic, and Delta Air Lines and agency partner Digitas. Ads partners who have participated include Adara, AdRoll, BlueKai, Chango, DataXu, Dstillery, Lotame, Quantcast, ValueClick, and [x+1].

Advertisers are being told to contact their account team for more info about getting started.