Date 
A defined time period that consists of a start time and an end time.
You use dates in calendar functions (for example, in activities), as well as for all dates that play a role in business transactions (for example, valid-to dates, cancellation dates) and in actions (date-dependent conditions).
A date is made up of a start time and an end time. The start time is within the time period, the end time is not. Dates that have the same start and end time are also called milestones.
Dates are further described by the date type and distinguished in the system by a unique indicator (GUID).
Dates need a reference object so that the system can interpret them uniquely.
Example
The end date of a contract with the reference object Main Partner refers to the time zone and the factory calendar of the sold-to party, and not to the time zone of the user who created the contract.
Note
The reference object for a date type can vary according to the date profile.
Examples of dates:
Valid from
Planned date of a sales visit
Signature date
Cancellation date