In a database, a surrogate key is essentially an identifier that uniquely identifies modelled things or objects. Surrogate keys may or may not be used as primary keys since they are not generated from any other data in the database.
It’s essentially a one-of-a-kind sequential number. A surrogate key denotes an entity that exists in the outside world and is modelled within the database, or represents an item within the database. Surrogate keys for individual objects or modelled entities are produced internally in these instances.