From Mac Guides
QuickTime 1.0 was released on December 2nd, 1991 for Mac OS 7. In November 1992, Apple released QuickTime for Windows. QuickTime 2.0 was released two years later, in February 1994 and November 1994 for Mac OS and Windows respectively, and was the only version of the software that was not available for free.
Updates of the software have continued to the present day, with the current version being 7.2, released on July 11, 2007 . QuickTime 5, released in April 2001, became the first version to support Mac OS X, while QuickTime 6.0.3 was the last to support classic Mac OS.
QuickTime Player and QuickTime Pro
Included with QuickTime is QuickTime Player, which allows the playback of multimedia formats supported by QuickTime. It includes free support for windowed and full screen playback of videos. QuickTime Pro is available for both Mac OS and Windows at a cost of $29.99 USD, and offers enhanced functionality to QuickTime Player and other components of QuickTime (such as its browser plugin). This functionality include support for recording, editing, saving and converting files.
The AAC encoder in QuickTime is a licensed technology. On Mac OS X, Apple covers the licensing, so applications that use Core Audio or QuickTime get AAC encoding for free, but on Windows, you must purchase a license to encode AAC (QuickTime Pro). Apple's iTunes software and iPod portable music player both natively support AAC encoding.