Phrase describing how for any category of product being sold there is much more aggregate demand for the non-hits than there is for the hits.
How does the long tail applies to keywords? Long Tail keywords are more precise and specific, thus have a higher value. As of writing this definition in the middle of October 2006 my leading keywords for this month are as follows:
|89||search engine optimization|
|73||latent semantic indexing|
|69||john t reed|
|64||google adwords coupon|
|15056||[not listed: 9,584 search terms]|
Notice how the nearly 10,000 unlisted terms account for roughly 10 times as much traffic as I got from my core brand related term (and this site only has a couple thousand pages and has a rather strong brand).