How to Animate in After Effects

In After Effects, you can animate a variety of properties of layers, such as position, scale, rotation, and more, using keyframes, expressions and animation presets

Keyframes are points in time where you specify a property’s value. 
When you create a keyframe, you are essentially setting a starting point for the property’s animation. You can then create additional keyframes at different points in time to specify different values for the property, and After Effects will automatically interpolate the values between keyframes.