Ever been to an auction? A bunch of people sit around while an auctioneer displays different items for sale. The auctioneer could start the bidding at $100 to see if anyone is willing to pay that price for a rare piece of art, for example. If multiple people want the piece, they can bid higher, offering $200, $300, or even more until no one else is willing to pay any higher. "Sold!" the auctioneer yells, usually with a bang of his gavel, and the highest bidder takes home the artwork. It's exciting for all, but especially for the winning bidder, who may have gotten a good deal on a very valuable item.

Keyword bidding is similar, but instead of bidding on art or antiques, you bid on keywords that you think will drive valuable leads to your website. It's an important part of a pay-per-click (PPC) strategy and requires careful thought to ensure you get the best leads for the best price.