In general, all auction sites play by the same rules. They operate based on a similar set of principles with which you should be intimately familiar if you intend to buy and sell safely and effectively. However, so you don't have to comb each site's terms of service agreements, we've done the dirty work for you and culled the most important facts. If you have anything to add, or if we've missed anything important, let us know!

Getting Started
Before logging on to an auction site, you should know there is more than just one type of site. Person-to-person sites and business-to-consumer sites and business to business sites. Sites can also be categorized as either larger, general interest sites (Lycos Auctions, CityAuction, eBay) or smaller, niche specialty sites (Pottery Auction, SportsAuction, Popula, IECvalue).

Once you settle on a site, you'll need to register. Registration is mandatory on every major auction site if you want to buy and sell merchandise. It's not a big deal, unless you are highly protective of your personal information, which in this case includes your name, email, address, phone number, and often your credit card number. Be aware that most services have privacy policies, which outline how they collect information about you from your computer (using cookies), and how they use your personal information. You should review these policies before registering. It's always free to look. Window-shopping doesn't require registration, and rubberneckers are free to browse the virtual aisles as much as they like. But if you do register, you must be at least 18 years old.

To complete the registration process, you'll have to agree to the site's terms of service or terms of participation.  This information will outline the site's dos and don'ts--mostly the don'ts--such as trying to manipulate prices, selling illegal goods, and other infractions we'll discuss later. In the case of a person-to-person site (eBay, boxLot, Yahoo Auctions), the terms are also painfully clear about the site's part in the transaction process. For the most part, auction sites function as middlemen--"just a venue," a third party that brings the buyer and seller together--and nothing more. By accepting their terms of service, you are effectively waiving their liability for your person-to-person transactions.

This frees auction sites from most legal responsibilities to the buyer; chief among them is not providing warranties on items listed and purchased on the site. In contrast, business-to-consumer sites (Onsale, Bid.com, uBid) list merchandise acquired directly from manufacturers and thus can include manufacturer warranties--something that's not an option for users who buy on person-to-person sites. All items are the property of the sellers, who are responsible for guarantees, refunds, and warranties. However, if you use a credit card with a buyer protection plan for the purchase, most issuers will automatically extend manufacturer warranties (often double the coverage period) and will provide some protection to the buyer to ensure the purchase is as agreed.

Auction sites also do not guarantee the legitimacy of either the items being sold or the sellers and buyers using the service. Users are responsible for judging the reliability of other members and their merchandise. However, some auction sites will arbitrate disputes between buyers and sellers. They will also refund fees in cases of deadbeat bidding or fraud, and offer insurance against fraud (beware of the deductible, though). And speaking of fraud: More and more sites are requiring more comprehensive user documentation in an attempt to crack down on shady sellers and buyers. Requiring a credit card for registration is becoming commonplace. (For example, in October 1999, eBay announced that it would be requiring credit cards for all new sellers.) Finally, all sites reserve the right to cancel your membership if you violate their terms.

As with any transaction-based service on the Web, you'll receive or create a password and username for yourself. Most sites let you change your password, username, email, and personal information. But if you do so, you might lose the positive feedback or rating you've earned from other members. Your username will likely be tagged with a symbol indicating a change in your account information.