The document discusses different types of multidimensional data models (MDDM) used for data warehousing. It describes MDDM as providing both a mechanism for storing data and enabling business analysis. The main types discussed are star schema, snowflake schema, and fact constellation. Star schema has one central fact table connected to multiple dimension tables, resembling a star. Snowflake schema is similar but dimensional tables are normalized into hierarchies. Fact constellation has multiple fact tables sharing some dimensional tables.