All services require you to submit your name, home address, phone number, email, and sometimes a credit card number. You must also submit or accept a username, which will be your screen name while bidding and selling, and a password, which allows you to bid and leave feedback. The large auction sites feature every type of item imaginable, from collectibles and antique curiosities to art and staple items, such as clothes, real estate, and cars. By far, however, the most popular category of merchandise on most sites is the collectible category. Sites that cater to a specific collectible are appearing more frequently.
Some auction sites restrict the auction of guns and pornography.
For instance, eBay has banned the buying and selling of any firearms, including antique guns. Auction Universe prohibits the listing of adult material. Obvious examples would include pirated audio, video, and software, all of which have explicit user agreements and copyrights, warning against their illegal duplication and sale.