Answer Description
Previously known as Windows Marketplace, the app and software store for Microsoft is now known as Windows Store. Update (Dec. 2017): Microsoft has renamed the Windows Store to the Microsoft Store. This question has been updated accordingly.
Wikipedia
Microsoft Store (formerly known as Windows Store) is a digital distribution platform owned by Microsoft It started as an app store for Windows 8 and Windows Server 2012 as the primary means of distributing Universal Windows Platform (UWP) apps With Windows 10, Microsoft merged its other distribution platforms (Windows Marketplace, Windows Phone Store, Xbox Music, Xbox Video, Xbox Store, and a web storefront also known as "Microsoft Store") into Microsoft Store, making it a unified distribution point for apps, console games, digital music, and digital videos E-books were included until 2019 Some content is available free of charge from the store
Microsoft_Store_(digital) - Wikipedia, the free encyclopedia