What is "postmodernism"? Be specific! !

Postmodernism is a historical concept, which refers to the post-industrial society or information age after World War II, and the related "Postmodernism" refers to a cultural and philosophical trend of thought in this social state. Postmodernism is a hot topic now. A set of "Post-modern Confrontation Series" published by Peking University Publishing House has made some introductions to this, so you can have a look.