QuickTime

QuickTime was a suite of multimedia features released by Apple. Its introduction came in the early days of multimedia on computers, when the possibilities of digitally-delivered multimedia were being explored. QuickTime was used as the basis of iTunes's audio and video playback functionality until version 10.5. The QuickTime movie file format (.mov) was used as the basis for the MP4 file format.

Early
Announced by John Sculley at MacWorld San Francisco 1991, it was initially released for System 6.0.7, and later ported to Windows 3.1 in 1992.

On 1999, QuickTime 4.0 introduced support for streaming video. The release was paired with the initial release of QuickTime Streaming Server, supporting the server-side components necessary to deliver streaming content.

Mac OS X
On 2001, QuickTime 5.0 was released with support for Mac OS X.

On 2002, QuickTime 6.0 introduced support for MPEG-4 video and AAC audio.

On 2005, QuickTime 7.0 was released.

End of Life
QuickTime 7 plug-ins are not supported by its successor, AVFoundation. Given extensive professional use of QuickTime 7, QuickTime 7.6.6 remained supported as a separately installable package until macOS Catalina, which removed support for all 32-bit software. On 2016, Apple released QuickTime 7.7.9 for Windows with a security update, officially discontinuing the product with the announcement.

QuickTime X
QuickTime X is the modern replacement for the original QuickTime software, included with macOS starting with Snow Leopard. It bears relation to QuickTime only in name - it does not use QuickTime frameworks at all. Rather, it uses the modern AVFoundation framework. It is a modern 64-bit Cocoa application, compared to the aging Carbon-based QuickTime 7 codebase. It does not support all codecs of, nor the plug-in functionality of QuickTime 7.