What Is Candidate Key In Dbms?

Candidate key is the minimum of the super key
and all candidate keys can use as primary keys....
But for a one table have a one designer so when designer chose a one candidate key as a primary key as his wish we call that the primary key of that table

A table may have more than one key,each key is  called a candidate key.
E.g( 1) A table CUSTOMER consists of columns: Customer_Id,name,Address etc..
Customer_Id is the only key (unique),thus a candidate key.

E.g(2) consider a table CAR where we can have 2 keys namely license_no,serial_no (which should be unique).
Both license_no and serial_no are candidate keys.

NOTE: In cases where we have 2  candidate keys as in e.g(2),one of the candidate key can also be a primary key.

I don't know pls explain me

A table may have more than one key,each key is  called a candidate key!