What are Long Tails?
Contrary to what many people believe, Long tail has nothing to do with the length of the search query. Even a short search term may be the part of long tail. The terminology has something to do with its graphical representation. If you plot keywords against search volumes, you will get a graph of Small number of Search Queries getting most of the volume, which shows as a Graphical Peak with steep slope downward, and a Long tail afterwards, with steady slope almost running parallel to the axis, representing terms which are Larger in number, but individually triggers very low volume of searches.
HistoryHistorically, it was Amazon, who discovered that a large number of their collection were unnoticed because of low volume of searches against them on homepage, and they can boost sales by presenting them alongwith their mainstream products. Individually, they have few seekers, but combined together they become huge!. Hence the term Long tail !
Importance and Targeting of Long Tail Keywords
What is of importance here is, in the Graph, Area under the curve represents, the Reach of your Ads. You can cultivate and grow this Long tail in the curve to such an extent that
Area (Long Tail Search Terms) > Area (High Search Vol.. Keywords) !
Can you afford to ignore them??
In Google Adwords, Google doesn't allow you to target most keywords which are part of this long tail, because they are huge in number and individually have very low search volume against them. Since, Google has to monitor ads targeting search queries for a large number of legal, ethical and safety parameters and requirements, it is not feasible for them to allow targeting ads on such queries. So, you find Low Search volume notifications against them. However, you may have your ads appear for these terms through broad matched similar looking keywords. That seems to be the only simple way of targeting Long Tails. Other way you can use Dynamic Search Ads, but then a lot depends on Data Structuring of your Website and Content Optimization.
Chances of appearing on these Long tail terms increases with better structuring of your adgroups. If your adgroups are well themed, giving clear cut message to the system, what they mean for, with respect to keywords, categories, situations etc., it will in most probability, occupy most of the Long tail terms, automatically. The Google, though in its documentations doesn't reveal much about the mechanism of how broad match keywords are matched, the point not to be forgotten is it always adds a factor, Other relevancy factors, in various documentations. So, actually it is all into the structuring of your Adgroups that gives the message of what is being targeted and where it can be matched and more important Projected ! You can fine tune it further by adding Nagative Matches or if you are willing to go farther, try Penumbra Match Type. Something, you should never forget, in adwords, it is actually the Good Structuring of Your Adgroup/Campaign, that leads you towards perfection in targeting, not by inserting a lot of keywords into your account.