An AET file is primarily an Adobe After Effects template project, functioning as a reusable starter setup similar to an AEP but meant to be opened repeatedly without overwriting the original, so After Effects treats it like a master you open and then save as a new project, containing the full “recipe” for the animation—comps, timelines, layer stacks, keyframes, effects, expressions, cameras/lights, render settings, and organizational elements like folders and interpretations.

In case you loved this article and you would like to receive more info regarding universal AET file viewer kindly visit the web site. An AET does not usually contain full footage, instead storing references or paths to external audio, images, and video, which is why template sets are bundled as ZIPs with Footage/assets folders and why After Effects reports missing items if things were renamed, and because AETs might rely on certain fonts or plugins, opening them elsewhere can trigger font swaps until everything is installed, and since file extensions aren’t exclusive, checking “Opens with” or the file’s source location is the best way to confirm the program behind it and what extra files should accompany it.

An AEP file represents the editable project you’re actively working on, while an AET is a reusable template, so in practice the difference lies in purpose: you open an AEP to continue that same project, but you open an AET to begin a new project instance so the original stays clean.

That’s why AET files are a staple for motion-graphics template packs (intros, lower-thirds, slideshows): the designer keeps the AET untouched as the master, and you begin each new video by opening it and doing Save As to create your AEP before customizing text, logos, colors, and media, and although both AET and AEP contain the same technical elements—compositions, layers, keyframes, effects, expressions, cameras/lights, and settings—and both refer to external footage, the AET protects the template while the AEP serves as the editable, ongoing production file.

An AET file retains the structure and animation logic of an After Effects project but not always the media assets, containing compositions with defined resolution, FPS, duration, and nesting, plus the complete layer arrangement—text, shapes, solids, adjustments, precomps, and placeholders—with layer properties like position, scale, rotation, opacity, masks, mattes, blending modes, parenting, and the project’s animation data including keyframes, easing, markers, and any expressions used to automate motion.

In addition, the template holds all effects and their configured values—whether color correction, blurs, glows, distortions, or transitions—plus any 3D setup involving cameras, lights, and 3D layer controls, along with render/preview preferences and project-level organization such as folders, labels, and interpretation rules, but it usually avoids bundling actual footage, audio, fonts, or plugins, relying instead on linked paths that can produce missing-asset or missing-effect warnings on another machine.