There were already Microsoft Stores for people in the U.K., Germany and Korea, and launched on Thursday.

"With this launch, our customers in the U.S. are able to buy first-party software and hardware directly from Microsoft offered in a comprehensive online catalog," said Trevin Chow, Microsoft senior program manager, in a blog post about the site launch.

Online shoppers in the U.S. have been able to buy and download some Microsoft software from the . But some Microsoft hardware, like the Xbox, has been available only from third-party retailers and is now for sale in the Microsoft Store.

People will be able to re-download software products that they buy for as long as Microsoft supports the product, typically five years, Chow said. Customers can also copy the software onto disks for future access.

Microsoft will store product keys for buyers, who will be able to access the keys online if they need to re-install the software.