what is CSDL, SSDL and MSL sections in an EDMX file?

• Conceptual Model(CSDL : Conceptual Schema Definition Language)
  The conceptual model contains the model classes and their relationships. This will be independent from the database table design.
• Storage Model(SSDL : Storage Schema Definition Language)
  The storage model is the database design model which includes tables, views, stored procedures, relationships and keys.
• Mapping (MSL : Mapping Schema Language)
  The mapping contains the information about how the conceptual model is mapped to storage model.