QTL is the extension given to files used by Apple QuickTime. QTL are files that are used to store links to movie files. This is a plain text file that, in addition to the location of the files, also tells you how QuickTime should play the movie. These can be parameters such as looping, displaying in a window or full screen, or closing the program after the movie ends.

Launching a QTL file automatically initiates the launch of the player and opening of the movie pointed to by the link in the QTL file.