Online auction sites typically have a privacy policy, and they post a link to its text on their main page. Yet, there is no such thing as guaranteed privacy in the online world. You can cloak your identity to some degree behind a screen name, a nondescript e-mail address, and a shipping address that is different than your home address. But even on so-called secure Web sites, such as those used by major auction venues, your personal and financial information is definitely not private.

Indeed, a Web site's privacy policy often spells out exactly how that site will share your information with other companies. For example, in agreeing to eBay's lengthy privacy policy during registration, you “expressly consent” to eBay's “use and disclosure of your personal information in accordance with this Privacy Policy.” Digging into the fine print, you will find that eBay shares information about you with subsidiaries and joint ventures all over the world. Information about you may be given to advertisers with your “express consent.” Also, your bidding and selling activities, feedback postings, and related comments will be visible on the site and accessible to anyone who uses eBay. Those who sell to you also will have your e-mail address, name, shipping address, and credit card information or bank account number, eBay notes.

The privacy policy for eBay is located on its Policies Page, accessed from the Policies link at the bottom of the eBay main page.

The eBay Privacy Policy page is accessed from the Protecting Your Privacy link on the Policies page.

According to eBay, people may browse the eBay site without identifying themselves or giving any personal information. However, certain types of information must be supplied before the buying and selling features can be used. Also, eBay automatically tracks certain types of information related to the behaviors of registered users on the site.

After reading eBay's privacy statements, if you still have questions, the Privacy page contains a link to eBay's Privacy Central. This page contains more discussions of eBay's privacy practices, plus information about third-party verification Web sites.

The business-to-consumer auction site uBid.com states in its Privacy & Security policy that products ordered at uBid sometimes are shipped directly from uBid's vendors, and certain user information is shared with the vendors to help them fill and ship orders. The site also assigns each new registrant “a random and anonymous customer number” that is used to track customer orders. The number also may be passed to third-party vendors and may be used “to measure traffic and visiting patterns on uBid and on other websites on the Internet.” It may also be used when statistics and other data regarding customer patterns are compiled.

Yahoo! cautions on its Yahoo! Privacy Center page: “Once you register with Yahoo! and sign in to our services, you are not anonymous to us.”

Take as many personal measures as possible to protect your privacy and the security of your financial information, and remain especially vigilant while using online auction sites. The sites' privacy policies will not guarantee anything except that they will try to protect your information — while making at least some of it available to others.