As recently as last year, search engine representatives were unclear or did not seem to care much about the search engine marketing application referred to as cloaking, IP delivery or stealth scripts.

At one point, I remember thinking many people working at major search engines must simply have no idea what cloaking is and how it works. If they had, they wouldn't have waited so long to take action against it.

Cloaking is a search engine optimization strategy in which a web page URL has several documents associated with it, one for each of the major search engines and a different document for end users.

With cloaking, an individual search engine spider sees only the page tailored to optimize rankings for that search engine.

Visitors entering a web site from search engine results see a page designed for end users because these click-throughs are URL independent, that is, the link from search engine results refers visitors to the URL of the site and not to the page the search engine has cached, which is the page optimized for its indexing process.

How Cloaking Works
Cloaking is a program installed on the web server that monitors URL requests. These requests must contain the IP address of the requester so the web server knows where to send the requested page.

By comparing the IP address of the requesting machine to a database of IP addresses of search engine spiders, the cloaking program determines whether a visitor is a search engine spider then decides which search engine spider it is.

The server sends the page designed for the spider it detects or the page designed for end users if a search engine spider is not detected.

Pros
Cloaking allows you to tailor web pages for individual spiders and to score top positions in multiple search engines using one URL.

It's difficult for a single page to rank well with all search engines because each search engine uses a different algorithm to rank web pages.

Hiding HTML code from prying eyes is the main reason people give for using cloaking. When sites achieve top search engine positions, competitors for the same keyword analyze the pages to discover why. Cloaking can keep important optimization strategies -- such as keyword frequency, keyword placement and word count -- hidden from competitors.

Cons
Though cloaking can keep competitors from some of your search engine optimization strategies, it can also be used to hide other things.

People can steal your site's content and hide it behind a stealth script. This nasty form of theft, referred to as page jacking, was exposed last year in a publicized event on Search Engine Watch.

But the major downside that may have you thinking twice about cloaking: Major search engines are finally on to it.

On the I-Search Discussion List, Marshall Simmonds, manager of Search Engine Relations at About.com, posted conversations he had with representatives from AltaVista, Inktomi and Northern Light. Sentiments expressed were simple and to the point: Web sites that cloak will be permanently banned from their search engine databases.

Google states its policy in a FAQ.

It all sounds like deterrent language to me.

Do Right by Users
Many people reported in I-Search that they achieve better positioning if they simply optimize normally and use techniques that are impossible with cloaked pages.

At several recent conferences, I've had the chance to speak frankly with search engine representatives. They generally agree you should provide quality content to your users and worry about spider-friendly design over positioning alone. This is a long-term strategy that will survive any spam shakeout.