One of Vista's most noticeable and memorable additions was the 'Aero' design, which used Direct3D to draw translucent, glassy windows that could fade gracefully in and out of view, replacing the 2D windows from older Windows versions. Longhorn was supposed to include a filesystem to replace NTFS, something we still haven't gotten almost two decades later. Microsoft planned a huge list of new features for Longhorn (and its planned successor, codenamed Blackcomb), many of which never saw the light of day. If you're interested in the history of Windows, you probably know a bit about ' Longhorn,' Microsoft's internal codename for the OS update that would eventually become Windows Vista.
