sql server - What's the difference between a Primary Key and Identity?

Question

In a SQL Server db, what is the difference between a Primary Key and an Identity column? A column can be a primary key without being an indentity. A column cannot, however, be an identity without being a primary key.

In addition to the differences, what does a PK and Identity column offer that just a PK column doesn't?

Answer 1

A column can definitely be an identity without being a PK.

An identity is simply an auto-increasing column.

A primary key is the unique column or columns that define the row.

These two are often used together, but there's no requirement that this be so.