Microsoft first announced Windows Store, a digital distribution service for Windows at its presentation during the Build developer conference on September 13, 2011.[6] Further details announced during the conference revealed that the store would be able to hold listings for both certified traditional Windows apps, as well as what were called "Metro-style apps" at the time: tightly-sandboxed software based on Microsoft design guidelines that are constantly monitored for quality and compliance. For consumers, Windows Store is intended to be the only way to obtain Metro-style apps.[7][8] While announced alongside the "Developer Preview" release of Windows 8, Windows Store itself did not become available until the "Consumer Preview", released in February 2012.[9][10]