In 2004, a South Florida woman listed a partially eaten grilled cheese sandwich on eBay. The sandwich sold to the highest bidder for $28,000. She believed, and showed in the auction's photos, that the sandwich had the image of the Virgin Mary in one of its slices of bread.

eBay homepage.  See more eBay pictures.

EBay is a global phenomenon -- the world's largest garage sale, online shopping center, car dealer and auction site with 147 million registered users in 30 countries as of March 2005. You can find everything from encyclopedias to olives to snow boots to stereos to airplanes for sale. And if you stumble on it before the eBay overseers do, you might even find a human kidney or a virtual date.

In this article, we'll find out how you can buy and sell items on eBay, examine how the bidding process works, look at ways you can protect yourself from auction fraud and take a look at the business and technology of the largest auction site in the world.