Fact Tables and Dimension Tables
In a dimensional model, fact tables always represent M:M relationships (see “Many-to-Many Relationships” on page 70). According to the model, a fact table should contain one or more numerical measures (the “facts” of the fact table) that occur for the combination of keys that define each tuple in the table.
Dimension tables are satellites of the central fact table. They typically contain textual information that describes the attributes of the fact table.