An AET file is a project template created by After Effects, a video production application. It contains a video composition template, which can be used as the starting point for making multiple .AEP video projects. AET files may include audio, images, and video clips, a timeline, and various effects that can be applied to the movie.

AET file open in Adobe After Effects CC 2017 The AET file is one of two file types used to save video editing project templates in After Effects. The main format is the AET file, which is saved in binary format. The other format templates may be saved in is the .AETX file, which is a text-based XML template. To create an After Effects project, select File → New → New Project then click File → Save or Save As → Save As... and choose "Adobe After Effects Template Project" from the "File Format" dropdown menu. To open an After Effects project, select File → Open Project....