STU files are Project files that have been created by Pinnacle Studio software. Pinnacle Studio is a program that is commonly used to create and edit videos. The STU file is used to store all relevant project information, including, but not limited to, video, audio, effects, and timelines. The STU file is then used to save and load video projects. STU files may be exported into a video file types such as .AVI and .M4V. STU File projects may also be burned to DVD and Blu-ray disc.