Master Calendar is used for the Date Fields... The purpose is to fill the gapes where there are no data and transactions for any particular date...
The base is Minimum Date and Maximum Date of your data model... By using the Loop, we can have All Dates from Minimum Date to Maximum Date...
Now using these dates, we can have Week, WeekDays, Month, Year, Quarter, MonthYear, YearMonth etc as a separate calendar table which is associated with the main/fact table with the Date field.. (same name)...
Hope this will make clear idea on using Master Calendar... You can also use the link provided by tresesco..
