Long tail keyword
Long tail keywords are the longer, more specific keywords that are less common, individually, but add up to account for the majority of search-driven traffic.
Long tail keywords are the opposite of "head" terms, which are more popular or more frequently searched on. For example, "fish tanks" is a head term, but "compare prices whisper aquarium filters" is a long-tail keyword.
Beginner search marketers often focus on head terms when optimizing their sites for organic search or creating pay-per-clickcampaigns. This is a mistake—long-tail keywords can offer incredible ROI because they're less competitive to rank for organically and less expensive to bid on for PPC. In addition, people using long-tail search queries are often highly qualified and more likely to convert.
The trick is to find a reliable, renewable source of longtail keywords that are relevant to your site and your business niche. Unfortunately, typical keyword suggestion tools don't deliver much in the way of long tail terms. They tend to return limited lists of very popular keywords, leaving you in the dark as to the long tail of search.