The CALENDAR function in DAX is used to create a calendar table in Power BI or Power Pivot. It generates a table with a single column that contains a contiguous set of dates. This function is particularly useful when working with time-based data, as it allows you to easily create a date table that can be used for time intelligence calculations.The CALENDAR function takes two arguments: the start date and the end date. It then generates a table with a date column that spans the specified range. For example, if you want to create a calendar table for the year 2021, you can use the following DAX expression:CalendarTable = CALENDAR(DATE(2021, 1, 1), DATE(2021, 12, 31))This will create a table with a single column named "Date" that contains all the dates from January 1, 2021, to December 31, 2021.Once you have created a calendar table using the CALENDAR function, you can use it to perform various time intelligence calculations, such as calculating year-to-date, month-to-date, or comparing data across different time periods.