Although eBay encourages the community to police the site, it also does its own investigations. Buyers beware: Violations are very easy to fall into, especially if you're new to online auction action.

Rules exist for buyers as well as sellers. If you are reported and found responsible for any of the following offenses, you may be subject to disciplinary action. Violations may result in the indefinite suspension of a user's account, temporary suspension, or a formal warning.

Here's the skinny on the kinds of buyer violations eBay looks into. Many of these violations go both ways. For example, if a seller e-mails you and offers to do a deal with you off the site, that's a violation from the seller's side.

If another eBay member pulls any of the following kinds of tricks with you, feel obliged to report him or her to eBay:

• Transaction interference: If anyone sends an e-mail to other buyers warning them away from a particular seller or merchandise, eBay will investigate.

• Off-site purchases: Contacting the seller and offering to buy (or sell) the item outside of eBay.

• Invalid bid retractions: Misuse of the bid retraction process is a serious eBay violation.

Every bid you place is a binding contract to buy. Even if eBay somehow didn't investigate you for retracting bids, the rest of the community would ostracize you -- eBay members show no pity for serial bid retractors.

• Non-payment after winning an item: If you bid or use the Buy It Now option, you must pay for your item. Again, refusing to pay for items not only gets you a scarlet letter, but also could result in your complete and total suspension from the eBay service. Forever. Period.

• Unwelcome buyer: If you bid or shop from a seller who clearly states terms that you do not fulfill, you'll be investigated. For example, Susie Seller can state in her item description that she refuses to sell to someone with negative feedback. If you have any negatives, then you shouldn't bid. If you do, and you win, you may be investigated.

If you really want the item, e-mail the seller and ask if you may bid on the item, even if you don't fulfill his or her terms -- it never hurts to ask.

Another common example has to do with international shipping. Say Steve Seller says that he will only ship within the United States, and you live in another country. If you bid and win the auction, you may be investigated.

• Bid shielding or shill bidding: Using a secondary ID to illegally manipulate the price of an item, without any intention of ever paying for it, is verboten and will be investigated.

Sometimes things happen, and you just don't know what to do about it. Maybe you have made a heinous mistake (who, me?), or you've seen something on the site that seems fishy. Who can you go to? Who's there to listen?

The Rules and Safety area of the eBay site has a support page where you may describe the problem using a series of drop-down menus. After using this system to explain your situation, you will usually get a response within 24-48 hours.

Here are some other options if you're seeking punishment for a deal gone bad:

• United States Postal Inspector: If your interaction involved the United States Post Office in any way, you can file a mail fraud complaint through the Postal Inspector's office. Your deal would involve the post office if you sent the seller payment through the mail and the seller sends you merchandise (or doesn't send at all) that is not what you ordered.

Call (800) 275-8777 or your local post office for the required forms and information. After you file a fraud report, the USPS contacts the alleged bad guy on your behalf.

• National Fraud Information Center: The National Fraud Information Center is based in Washington, D.C. This organization collects reports of fraud and transmits the information to the National Fraud Database, maintained by the Federal Trade Commission and the National Association of Attorneys General. You can file your report online at The National Fraud Information Center or you can call (800) 876-7060.

The information you provide by filing a complaint with the NFIC informs federal and state regulators of potential illegal activities. It will not, on the other hand, get you your money back. By just reporting fraud, you can help prevent wrongdoers from victimizing others.

• Local law enforcement agencies: Contact the District Attorney or state Attorney General's office in the seller's city and supply as much information as these officers will take. You may also want to try the state's consumer affairs department — just run a Web search with the state's name and consumer affairs. Again, this option probably won't get you your money back, but may make you feel better.

• FTC Bureau of Consumer Protection: The Federal Trade Commission (FTC) Bureau of Consumer Protection runs a popular Web site that takes complaints on fraud of all kinds.

The FTC, in turn, works with many other leading crime prevention organizations. The FTC will send your information to all interested law enforcement organizations through its Consumer Sentinel.

There's a good deal of solid information (some pretty scary information, as well) on this site. Check it out and help the good guys!