A little bit of original research for you today. How important are the "most important" search terms in driving traffic to your website? I've been doing some analysis on a website whose visitors are primarily from the engineering and scientific sectors, and which gets tens of thousands of visitors a month from Google. I exported the search terms which visitors from Google had entered in February 2010, and the number of times each one cropped up. Here's what I found.
The number of different search terms was about 40% of the total number of visitors sent by Google. Or put another way, each search term sent around 2.5 visitors. However, it was not an even distribution. The top 20 most commonly-used search terms accounted for just under 25% of visitors on their own, but then there was an incredibly "long tail" of well over 10,000 more, less frequently-used terms, accounting for over 75% of visitors. What we can take away from this (and it'll be no surprise) is that to catch a decent amount of traffic, we have to spread our net widely. It's all about the number of words, and combinations of words, on our website. The more we have, the more chance we give ourselves of catching the huge number of unique searches made each month.
What I really wanted to look at, however, was the complexity of the searches. We tend to focus our efforts on simple 1- and 2-word phrases, but are searches that simple? It would seem that they're not. In fact, 1-word search terms, which represented just 5% of the total number of different terms used, sent about 22% of visitors. Search terms of 4 or more words represented 45% of the total number of different terms used, and sent more visitors than 1-word search terms: 24% of all traffic.
So, traffic was divided fairly evenly between 1-, 2-, 3- and 4-or-more-word search terms. We can assume that the shorter the search term, the greater the competition, so that's a real reason to pay more attention to the longer ones. With there being so many different long search terms, however, it's once again all about having the content.