Ever since Google announced the impending demise of the AdWords Keyword Tool and their preference for its new avatar – the Keyword Planner, yet another hot discussion has sprung up in the SEO community. This time, strong adherents of the free-for-all ideology are riled at Google’s decision to make the Keyword Planner accessible only to marketers who’ve explicitly signed up to Google’s AdWords (which is one step more than having a Gmail account), taking it closer to being a paid tool in future! I don’t see this as a hindrance, because most other keyword (or other) tools require you to create an account and sign in before you can use them, even if they’re free. But if Google does it, we have reason to pounce on them, don’t we?
Using the good ol' free Google Keyword Planner is great. But there is an alternate universe of Long Tail keyword phrases that live in Google's other database--namely, their "Autocomplete database." That's the database that is accessed when you're typing queries into the Google search box (notice that list of suggested keywords that pop up as you type?)
So which tool should you use? The simple answer is ALL of them!! If the data from several tools suggests that a keyword may be a good keyword to target, than you should feel fairly confident that it is. If your results appear to be contradicting one another for a particular keyword, then you may want to be hesitant in including that keyword in your selection. SEO professionals should never rely on one resource for research. No one tool is going to be 100% accurate and you stand the best chance at making the correct strategic decisions by using a variety of sources.
If you don't know the difference between head terms and long-tail keywords, let me explain. Head terms are keywords phrases that are generally shorter and more generic -- they're typically just one to three words in length, depending on who you talk to. Long-tail keywords, on the other hand, are longer keyword phrases usually containing three or more words.