Hierarchy: The hierarchy contains all the objects and items in the scene both in games design and 3D modelling. It also stores groups and items in those groups under pop down menus to keep the hierarchy tidy and organised. This can be used to quickly access parts of the scene you can’t see easily or are far away.
Parent and Child: When you group a bunch of objects the top object becomes known as the parent and all the objects below that are called the children. The children can be shown or hidden based on a drop down menu that is on the parent object. To create groups you can use keyboard short cuts or generally, in most programs drag the object you want to be a child of an object onto the object you want as a parent.
Character Set: A character set is important as usually when you set a key frame it only sets it for the object you have selected which means only that object would move. These character sets make it so that every object in that character set will also have a key frame set for the meaning everything should move as you intended if you have objects moving using parent and child.
Deformers: There are many different deformers such as the bend tool. Deformers like these can be found under the deformer option in the animation editor. A vast majority of these can also be animated with some needing a little more set up to use than others.
Pivots: These are the points by which object a are manipulated from, scale can increase distance from the pivot or influence what side you want to have the size increase or rotation where you want to rotate an object about a certain point depending on where you want the model to rotate from in your animation.