In this Free Video Tutorial Tutorial Ian Robinson Talks about the fundamentals of After Effects.
This is a great starter video! Highly recommended to every beginner.
Way more interesting than a plain manual.
Besides, Ian’s voice is extremely smooth and easy to follow.
So, if you want to know What is After Effects just hit that play button !
Or this is what Wikipedia says:
Adobe After Effects is a digital motion graphics, visual effects and compositing software package published by Adobe Systems, used in the post-production process of filmmaking andtelevision production. Its main uses are the origination of 2D and 2.5D animation, visual effectscompositing and finishing (image adjustment, color correction etc.). After Effects can also be used as a basic non-linear editor and a media transcoder.