What is the meaning of “last but not least”?

The expression has been around since the 16th century. It means “finally, but not less importantly.” The expression can be used when you introduce a group of people to a friend. When you come to the last person in the group, you can say “last but not least, this is Suman”. What you mean by this is that though Suman is the final person to be introduced, it doesn’t mean she is less important than those introduced before her; she is as important as the others.

 Source: ‘Know Your English’ ( The Hindu) – July 16, 2007