One of the most fundamental concepts in Algebra is the concept of a set. This video introduces the concept of a set and various methods for defining sets.

Tutorial: Number Systems & Sets.
Integers, Rational Numbers, Natural Numbers etc... More free lessons at: http://www.khanacademy.org/video?v=eF6zYNzlZKQ Note: All Khan Academy content is available for free at (www.khanacademy.org)