[Definition] An artificial key made from data that is system assigned or generated when another candidate key exists. Surrogate keys are usually numeric ID values and often used for performance reasons.[citation needed] [Key Name] 
Surrogate
S i m p l e
C o n c a t e n a t e d
C o m p o u n d
C o m p o s i t e
N a t u r a l
S u r r o g a t e
C a n d i d a t e
P r i m a r y
A l t e r n a t e
F o r e i g n