What is the difference between a primary key and a surrogate key?

Question

I googled a lot, but I did not find the exact straight forward answer with an example.

Any example for this would be more helpful.

Answer 1

A surrogate key is typically a numeric value. Within SQL Server, Microsoft allows you to define a column with an identity property to help generate surrogate key values.

The PRIMARY KEY constraint uniquely identifies each record in a database table. Primary keys must contain UNIQUE values. A primary key column cannot contain NULL values. Most tables should have a primary key, and each table can have only ONE primary key.

http://www.databasejournal.com/features/mssql/article.php/3922066/SQL-Server-Natural-Key-Verses-Surrogate-Key.htm