Surrogate key, also known as dummy key, non-natural key, artificial key or identity key, is a substitution for the natural primary key. In DW, we typically use a surrogate key for the dimension tables primary key. They join the dimension table to the fact table.
Generally, OLTP source system primary key should not be used as the primary key of the dimension table. Surrogate keys are maintained within DW instead of the natural keys taken from source data systems.
Data warehouses commonly use a surrogate key to uniquely identify an entity. A surrogate is not generated by the user but by the system. A primary difference between a primary key and surrogate key in few databases is that PK uniquely identifies a record while a SK uniquely identifies an entity.
E.g. an employee may be recruited before the year 2000 while another employee with the same name may be recruited after the year 2000. Here, the primary key will uniquely identify the record while the surrogate key will be generated by the system (say a serial number) since the SK is NOT derived from the data.
There is an E Book THE MULTIDIMENSIONAL DATA MODELING TOOLKIT where you can find the details of SURROGATE KEY and the book is available at