Correctly dealing with dates and time is critically important in data warehouses. In the end, you should understand that this is one of the most important attributes in a majority of fact tables in your DWH, which defines the "position" of your data records. Lots of reports are filtering data by date-time fields before performing data aggregation. This is probably why Data Services has a decent amount of date functions, allowing a variety of operations on date-time variables and table columns.
Data Services supports the following date data types: date, datetime, time, and timestamp. They define what part of time units are stored in the field:
date: This stores the calendar datedatetime: This stores the calendar date and the time of the daytime: This stores only the time of the day without the calendar datetimestamp: This stores the time of the day in subseconds