Windows NT is a series of Microsoft's Windows operating systems written in the C and C++ programming languages. They were the first to use their new 'NT' (New Technology) core. That means it had a brand new core to do more things than the MS-DOS-based one that they used in older versions of Windows. Also, it was more secure and crashed less. Windows NT 3.1 was released as alpha versions in 1991-1992 and beta versions in 1993.