identity increment and identity seed in sql server

Syntax

IDENTITY [ ( seed , increment ) ]

Arguments

seed

Is the value that is used for the very first row loaded into the table.

increment

Is the incremental value that is added to the identity value of the previous row that was loaded.

You must specify both the seed and increment or neither. If neither is specified, the default is (1,1).

References: http://technet.microsoft.com/en-us/library/aa933196(v=sql.80).aspx