What is Dimension Table?
A dimension table holds the descriptive attributes of the things in your facts, such as customers, products, locations or dates.
Dimension Table explained
Dimensions are what you group and filter by: country, product category, month, sales rep. They tend to have fewer rows than fact tables and change slowly.
When a dimension attribute changes over time (a customer moves region), teams decide whether to overwrite it or keep history; the choice changes what historical reports show.
Example
A product dimension lists each product with its name, category, brand and launch date, so sales facts can be grouped by category.