Shill bidding is when the seller of an auctioned item has a third party (usually a friend or just himself with a second account) bid on his item to artificially drive the price up, thus ensuring a minimum price for the lot and forcing the person willing to buy the product to pay more than the price he would have paid without shill bidding. Shill bidding is an illegal practice, whatever the online auction platform or auction house. See also: Shill bidding policy on eBay