Using online keyword tools can help you in a multitude of ways. First, they will give you tips on similar or related words, phrases or word groups for your product or service. Then, they can help you determine which among these are popular. Also, some will help you estimate the importance—and therefore the cost—of your desired keywords in the hierarchy of things.

Two of the most popular free tools are Google’s own AdWords Keywords Tool, and Overture.

Google AdWords Keyword Tool. Simply type in any, and any number, of your desired key words or phrases, and this tool will come up with other, related possibilities, with visual indicators of popularity (how many times that keyword is searched relative to others), competition (how many other advertisers use this key word or phrase), and will allow you to add the keywords outright with a simple click of an “add” button. You have options such as constraining your search to a broader or more limited set.

Overture Keyword tool (now Yahoo Search Marketing). Overture used to be a search-related marketing company until it was acquired by Yahoo! and then subsequently developed as its own Gogle AdSense-like service. While the Overture keyword tool is not free, publishers and advertisers on Google AdSense can likewise sign up for an Overture account. What’s great with Overture’s keyword tool is that it actually shows how often a keyword has been displayed and saearched for.