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

I think Michelle Poolet describes it in a very clear way:

A surrogate key is an artificially produced value, most often a system-managed, incrementing counter whose values can range from 1 to n, where n represents a table's maximum number of rows. In SQL Server, you create a surrogate key by assigning an identity property to a column that has a number data type.

http://sqlmag.com/business-intelligence/surrogate-key-vs-natural-key

It usually helps you use a surrogate key when you change a composite key with an identity column.