timestamp
timestamp is a data type that exposes automatically generated binary numbers, which are guaranteed to be unique within a database. timestamp is used typically as a mechanism for version-stamping table rows. The storage size is 8 bytes.
Remarks
The Transact-SQL timestamp data type is not the same as the timestamp data type defined in the SQL-92 standard. The SQL-92 timestamp data type is equivalent to the Transact-SQL datetime data type.
A future release of Microsoft® SQL Server™ may modify the behavior of the Transact-SQL timestamp data type to align it with the behavior defined in the standard. At that time, the current timestamp data type will be replaced with a rowversion data type.