In a partnership between Amazon and Twitter, users of both get a unique—albeit fairly specific—ability: If you spot an Amazon product link on Twitter, you can now add it to your shopping cart just by responding to the tweet with the hashtag #AmazonCart.

In order for this to work, of course, you have to connect your Amazon account to your Twitter account—which you can do at Once you’ve replied to a link, the item will appear in your cart the next time you visit Amazon’s site. You’ll also be notified via email and in a reply tweet from @MyAmazon that a product has made its way into your cart.

If you don’t yet have your Twitter and Amazon accounts linked and you send an #AmazonCart tweet, you’ll get a reply from Amazon asking you to set up the service.

At first, the social shopping cart will only be available to those in the U.S. and in the U.K.—where the hashtag will be #AmazonBasket.

While the hashtag system is an easy one to use, it is a public broadcast of what you hope to buy, not to mention free advertising for Amazon, powered by you and your tweets. Julie Law, an Amazon spokeswoman, said that the Twitter collaboration isn’t about turning customers into promotional machines, though.

“There’s a public nature to social media, particularly with Twitter—which doesn’t have the barriers of other social media tools,” Law said. “We have a significant number of customers who use Twitter, and a significant number of affiliates who use Twitter, too.” Both parties, she said, already share Amazon links on Twitter all the time. “So to be able to allow customers to add something to their Amazon cart without leaving Twitter was sort of a logical step,” Law said.

There is one area of Amazon’s online storefront that won’t play nicely with #AmazonCart or #AmazonBasket: Lightning Deals. Each day, Amazon offers products at a discounted price for an hour or two at a time under this promotion. If you tweet a link to a Lightning Deal with the corresponding U.S. or U.K. specific hashtag, the product won’t end up in your shopping cart. The deals exempt because the promotion only lasts a certain period of time, and sometimes is only offered in limited quantity, Law said.