What is an aucton?

When you hear the word “auction” – what do you think of? Do you think “opportunity?” Do you think “rare and unusual items?”
When I hear the word "auction", I think of antiques. I envision sitting in a room where people are competing to be the highest bidder for a 200 year old painting or something, and spending thousands, or even millions of dollars for these items. Its weird! :-/