What was the code name for Windows 10?

The code name for Windows 10 was Threshold. Microsoft used the name during development before announcing the operating system publicly in 2014.

Threshold was part of Microsoft’s effort to unify the Windows experience across PCs, tablets, phones, and other devices. The project followed Windows 8, whose touch-focused interface and Start screen had divided opinion among desktop users. Windows 10 restored a more familiar Start menu while retaining several touch-friendly ideas from Windows 8.

Microsoft introduced Windows 10 at a September 2014 event and released the desktop version on July 29, 2015. It was initially presented as a major platform intended to evolve through regular updates rather than through entirely separate versions every few years. The company later shifted to additional internal code names for major development branches, including Redstone.

Vienna was an earlier code name associated with a planned Windows release that became Windows Vista. Blue referred to an update cycle associated with Windows 8.1. These names are easy to confuse because Microsoft used many internal project names during the development of different Windows generations.