The Sequence object was introduced in SQL Server 2012. This is a separate schema object that produces a sequence of numeric values, similar to the way an identity works. A sequence is a separate object, however, and it produces values independent of a table. The next value in the sequence can be retrieved before an insert, and the sequence can be shared by multiple objects. The use and behavior of the sequence is controlled by the application, but the behavior needs needs to be understood and considered by the developer.
This article looks at the basics of the sequence object,