Null set-empty set
universal set-set that contains all object under consederation
proper set-elements does not belong to the group
subset- set of all elements
set- is a well difined groups of objects.
What is a set? Well, simply put, it's a collection.First you specify a common property among "things" (this word will be defined later) and then you gather up all the "things" that have this common property.For example, the items you wear: these would include shoes, socks, hat, shirt, pants, and so on.I'm sure you could come up with at least a hundred.This is known as a set.Or another example would be types of fingers.This set would include index, middle, ring, and pinky. So it is just things grouped together with a certain property in common.