DAX SUMMARIZE Function is categorized under Filter functions. This function can be done with ROLLUP function also.

Purpose of DAX SUMMARIZE Function
The SUMMARIZE helps to get a table with the selected columns for the groupBy_columnName parameters and the summarized columns designed by the name parameters.
Return value
The DAX SUMMARIZE function returns a summary table for the requested totals over a set of groups.
Syntax
= SUMMARIZE(<table>, <groupBy_columnName>[, <groupBy_columnName>]…[, <name>, <expression>]…)
Arguments
Arguments | Description | Remarks |
table | Any DAX expression that returns a table of data. | Mandantory |
groupbyColumnName | The qualified name of an existing column to be used to create summary groups based on the values found in it. This parameter cannot be an expression. | Optional |
name | The name given to a total or summarize column, enclosed in double quotes. | Mandatory |
expression | Any DAX expression that returns a single scalar value, where the expression is to be evaluated multiple times (for each row/context). | Mandatory |
Usage notes
- An error is returned if each column for which you define a name does not have a corresponding expression. The first parameter, ‘name’ defines the name of the column in the results.
- The second argument, ‘expression’ defines the calculation performed to obtain the value for each row in that column.
- groupBy_columnName must be either in a table or in a related table to table.
- Each name must be enclosed in double quotation marks.
- One row is returned for each group.