File with an .AEP extension contains a professional video project with sounds, images and a timeline on which there are inserted transitions and applied effects, stored in a binary format. There is also a possibility to save such data in a similar AEPX text format (based on XML), which is a second major project format supported by After Effects.

Adobe After Effects software is designed to create and edit professional videos. It also enables saving projects as templates available to be used with other videos, in a binary AET format and text – AETX (based on XML).