Definition: Long tail keywords are specific search terms that imply increased intent and focus over shorter head terms. Generally considered to be three or more words, long tail KWs are the primary focus of most online stores seeking visibility in a niche or focused vertical.
Head terms are broad and short, often revealing little about topic and intent.
Head: "shoes" or "nike shoes"
Long Tail: "buy Nike Air Jordan IV size 4" or "Nike Air Jordan size 9"
The long tail variety specifies what the user is looking for and what their intention is. Even if buy-oriented verbs aren't included in a term, the specific query itself indicates more intent than a head query such as "shoes."
To maximize search engine visibility, conduct thorough keyword research to compile a list of all long-tail keywords relevant to a business' products and vertical market. Less-competitive terms afford more opportunity for high ranking. Take both organic and paid search into account — some terms may be pricey to bid on, while the domains that rank high in organic search aren't particularly strong or well-established.
Marketing-savvy businesses conduct paid and organic keyword research inform their product catalog, enabling them to predict CPA and build inventory on items that present an immediate opportunity for positive ROI.
Some long-tail keywords have little paid competition, while others are surprisingly expensive. Every vertical market and type of product is unique. Use Google AdWords' Keyword Planner is a quick and effective way to gauge the competitive landscape and evaluate which keywords a business should consider bidding on. Entering head terms into Google and making note of Google Suggest results is a general indicator of which long tail keywords receive consistent search volume. You can also use keyword tools to spy on competitors and see what strategies they're using.