Set Theory deals with collections of objects called sets.  An object in a set is called an element.  Sets can contain anything: numbers, letters, colors, dog breeds, types of food, etc.  Sets can be compared to see how they are the same and how they are different.

Intersection and Union of Sets

Watch a Khan Academy Video » Length: 7:43

Relative Complement or Difference Between Sets

Watch a Khan Academy Video » Length: 6:14

Universal Set and Absolute Complement

Watch a Khan Academy Video » Length: 6:25