What are the functionalities of groupby in LINQ?

In LINQ, the GroupBy operator is used to group elements in a sequence based on a specific key and returns a sequence containing the groups. GroupBy’s functions include:

1. Grouping: Elements are grouped into multiple groups based on a specified key.
2. Key selection: Keys can be selected based on the properties or expressions of elements as the basis for grouping.
3. Element selection: choose which elements to include in each group.
4. Anonymous types: You can use anonymous objects as keys for grouping, combining multiple attributes or expressions together.
5. Element count: allows counting the number of elements in each group.
6. Total elements: aggregation operations such as sum and average can be performed on each element within a group.
7. Group sorting: Groups can be sorted to return in a specified order.
8. Filtering by group: Groups can be filtered based on specific criteria, returning only the ones that meet the conditions.

By combining different operations, one can flexibly utilize GroupBy to achieve various grouping and aggregation functions.