Granularity in data warehouse

What does the granularity in the data warehouse mean?

Granularity is one of the most important aspects of data warehouse design. Granularity refers to the level at which the data stored in the data unit of the Data Warehouse is refined or comprehensive.
The higher the level of refinement, the smaller the level of granularity. On the contrary, the lower the level of refinement, the larger the level of granularity.
Data granularity has always been a design issue. In an early operating system, the granularity is used for Access authorization. When detailed data is updated, it is almost always stored at the minimum granularity.
However, in the data warehouse environment, the granularity is not assumed.
In the data warehouse environment, granularity is the main design problem because it deeply affects the size of the data stored in the data warehouse and the query type that the Data Warehouse can answer.
The data volume in the data warehouse must be weighed against the query details.