This happens every day because of a perfectly legitimate process known as "drop catching," where people quickly snag the domain names owners have let expire and try to resell them or use the links associated with the names, which could be extensive, to create Web sites loaded with advertisements. You can easily avoid becoming a victim of a drop catcher by better understanding how the domain registration system works to protect your domain name.

Your Web site, with all the content you have so painstakingly added, sits on a computer with a unique address called an IP address, which is simply a series of numbers. A domain name is an address forwarding service that directs visitors to the site using this IP address. Domain names are used instead of numbers because most people find it easier to remember a name rather than a bunch of numbers. It's as if you could dial your friend's name into the telephone instead of his phone number.

You can purchase a domain name by registering it with a provider of domain services such as GoDaddy.com , the largest on the Web, or any number of other registrars. The name can be registered for just one year, for about $10, or for as long as ten years, for around $80. Many register for only one year because it's cheaper, or they only want the site for a limited time.

At the end of the year, the registrar usually sends an email renewal notice to the owner. If the owner doesn't respond to the renewal notice, the domain name will eventually be made available for purchase by someone else. Roughly 20,000 domain names become available every day because the owners allowed them to expire, or the owners didn't realize that their domain name was up for renewal

According to the rules established by the Internet Corporation for Assigned Names and Numbers(ICANN), domain registrars have 45 days after the expiration date to notify the owner that their domain name is going to be dropped from the registry. If the name is dropped, the guidelines then call for a 30-day grace period during which the owner can still claim the name. After this grace period and then another five-day holding period, the name is dropped from the registry and anyone can claim it.

Since 2004, however, a number of domain service providers, starting with SnapName.com, have created an auction process for expired names which bypasses the original drop process and makes the names available in as little as thirty days. GoDaddy.com begins the auction process even before the names have officially expired, although it does warn the auction participants that the owner could still claim their name.

These providers of domain services each have tools on their sites to make it easier to grab expired names. They provide constantly updated lists of expired names, various auction services, search engines, and other free tools for anyone to quickly and easily find available domain names. Some sites also offer software for sale that further simplifies the search for expired and soon to be expired names.

With the surge in online advertising, drop catchers will continue to seek out domain names from sites with good traffic, anxious to exploit the established links. Protect your site and your business by checking the expiration date of your domain name. Relying on the registrar to send a renewal notice that could easily be sent to an old email address or get lost in the spam catcher, could cost you years of hard work.