Irfan Ahmad shares this useful information about longtail keywords and why they are necessary:
There are short-tail (broad) and long-tail (narrow) keywords. Short-tail keywords are broad but short terms your customers would use to find you. For instance, if you operate a plumbing business a short-tail keyword might be “plumber” or “Tampa plumber” adding in location to direct search traffic a little more efficiently.
The problem with short-tail keywords is that they can be highly competitive depending on your field. For instance, a home designer may be competing with large-scale operations like Houzz and other sites that have much larger paid search budgets. You will, most likely, never outrank them.
That’s one of the reasons why long-tail keywords have become so important. Long-tail keywords allow businesses to rank for the language and phrases people are using in a search. To be considered a long-tail keyword, the phrase is generally over three words. Long-tail is more targeted than short-tail and addresses what people are looking for. Long-tail keywords often get at a problem. For instance:
Short-tail keyword: Tampa plumber
Long-tail keyword: solutions for clogged pipes
In this example, the searcher will find pages and pages of Tampa plumbers. It may even pull up plumbing supplies or other key terms that have a business overlap. You’ll find a big name, national plumbing franchises, as well as national companies who work with plumbers like Angie’s List, Yelp, and the Better Business Bureau. The list can be overwhelming for some users, and so they are apt to select the first couple on the list. If your search engine optimization hasn’t placed you there, you’re out of luck…
Go to the source for more: Long-Tail Keywords: What They Are and Why You Need to Use Them (SEO Tips)