Modernism and post modernism are two terms that are so broad that they become a hard concept to grasp.

Modernism can be defined "as a deliberate philosophical and practical estrangement or divergence from the past in the arts and literature occurring esp. in the course of the 20th century and taking form in any of various innovative movements and styles."

This differs from post modernism because obviously this deals with the changes in our culture after the 1970's. All changes in culture, technology, entertainment and more has contributed to post modernism.