Working with Masks and Transparency

Understanding transparency in After Effects
Transparency terminology in After Effects
Using a footage item with an alpha channel
Working with masks
Creating masks
Drawing rectangular and elliptical masks
About mask paths
Drawing a Bezier mask with the pen tool
Selecting masks and vertices
Scaling and rotating selected masks or vertices
Changing the shape of a mask
Feathering mask edges
Adjusting the edges of a mask
Adjusting the opacity of a mask
Applying motion blur to a mask
Specifying which parts of a mask are inside and outside
Moving a mask and panning a layer behind a mask
Specifying one mask as the target for animation
Animating a mask
Using Smart Mask Interpolation (Pro only)
Importing masks from Adobe Illustrator and Adobe Photoshop
Applying effects to a mask
Creating visible lines and solid shapes from masks
Controlling how masks in the same layer interact
Using mask modes
Modifying multiple masks
Locking a mask
Reusing a mask
Creating track mattes and traveling mattes
Using blending modes
Creating transparency using keying