Is search marketing old enough to have a good old days? If it is, then I remember them. Ah, the days when you could fire up the Overture keyword tool to see how many searches were done in the U.S. on Yahoo! for a particular keyword. Add a little math, and you could estimate the number of searches done across all U.S. search engines in a month. But then Yahoo! crippled that free tool, and we've been left with no way to project keyword demand, until now.

Bill Hunt, my co-author of Search Engine Marketing, Inc. worked with his team at Global Strategies International to estimate keywords using Google's free keyword tool. The good news is that this technique allows you to estimate keyword demand for any country where Google is used, not just the U.S., but the bad news is that it is an arcane and time-consuming procedure that requires you to click your heart out before you extract the information.

If you're wondering why you'd want to project keyword demand, that's simple. Keyword demand is the number of searches on a particular search keyword done in a period of time, such as "3,000 U.S. searches per month for the keyword Mike Moran" (I wish). By understanding the number of searches for a keyword, it can help you know which ones are most worth concentrating on.

For example, years ago when I worked with IBM to sell their ThinkPad computers online, it was extremely valuable to know that the keyword laptop was far more popular than notebook because then we could optimize for the word that more searchers used.

But you can do a lot more with keyword demand. If you have an estimate of how many searches are done each month, you can take guesses at how many visitors you might get to your site by improving your search marketing. And you can project from there how many people might buy something. Keyword demand is the basis of convincing yourself that the time, effort, and money required for successful search marketing is worth it.

Before moving on to the procedure, remember that even though we are using Google's tool, Google is not promising that any of these numbers are accurate—in fact, there's no real way to test the accuracy of these numbers anyway. But it gives you a good idea of where you stand—better than any other free tool can do.

Oh, and one more thing: What Google giveth, Google can taketh away. eth.

At any moment, Google might decide to change the way its tool works. If that happens, we'll try to update the procedure so that you can do something else. But as we found out with Yahoo!'s treatment of the Overture tool, it's hard to know what to do when the old method breaks. At first, the Overture keyword tool became a bit unreliable—it ran slowly and started to time out a lot—then the numbers were frozen in time in January of 2007. Later in 2007, the URL begin to yield 404s all the time. To this day, I am not sure that Yahoo! has made any announcement that the tool was ever withdrawn. The same thing could happen to this procedure that works with Google's tool.

But, at least it works now, and it is the best free alternative you've got. If you're willing to pay for information, Wordtracker, Trellian's Keyword Discovery, and other tools provide numbers that help you estimate keyword demand, but my favorite price is always free.

So, check out the free guide to estimating keyword demand. Let me know if it works for you.