Case study- Elements of motion graphics

2D ELEMENTS
2D elements are shown on the X and Y axis and they are normally 3 and 4 sided shapes. There are 3 different types of 2D elements. 
Shell: This is linear meaning the values on the x and y are consistent. 
Solid: This is a two dimensional element which is quadrilateral or triangular. 
Plate: This is also 2 dimensional but represents a solid on X and Y axis. 

3D ELEMENTS
3D Elements are not technically they create and illusion that an image has depth. This object is displayed also on the X and Y axis but also on the Z axis. 
MATTES
A matte is the process of blanking part of an image so that is may be replaces with a different picture. This is done using a mask to cover the specific area. It's used to create one final image combing more the one other image. It is used in special effects to mask particular areas in a shot. 
ALPHA CHANNELS
This is a channel mask. It can change the transparency of an edit. Alpha channels define an area as an 8 bit grey. A mask is created by duplicating a colour channel and editing it with a variety of tools. 
KEY FRAMES
Key frames are shown by small diamonds in the time line. They are created to mark points of transformation. It is most often used in animation. You would put a key frame at the begging of the time lie with the starting position for your character and then a few frames or seconds later you would adjust the position,scale,rotation or opacity of the character or object you wish to animate. 
LAYERS
Compositions are made up of layers. Imported items are known as separate layers.  Flat images can not be separated but PSDs can be to be edited. You can also create more layers in after effects such as cameras, adjustment layers, lights, null objects, text and shapes.
COMPOSITE MODES
This is the different types of combining composites into one composition. 
Normal,Add, Subtract,Difference,Multiply,Screen,Overlay, Hard light, Soft Light, Darken and Lighten. 

The variations are determined on the colours and how they react.