From Adobe Systems:
As the name suggests, this application allows you to apply effects, composites, and animation for film, video, multimedia, and Web projects. Compositing features include unlimited layers, Bezier masks, alpha-channel controls, antialiasing, interlayer transfers, and the ability to mix multiple file resolutions. Unlimited key frames can be added to animate all layer attributes, including position, rotation, scale, anchor point, and opacity. Layers can be positioned and animated within one one-thousandth of a pixel.
In addition to more than 60 special effects, time remapping can be used to create such effects as variable slow motion, frame stuttering, playback delay, backward playback, and hold frames. Adobe After Effects can be seamlessly integrated with Adobe Photoshop, Adobe Illustrator, and Adobe Premiere.