Long-tail keywords, in the context of advertising and SEO, are detailed keyword phrases that a potential customer might use to search online when ready to purchase.
Knowledge about purchase intent is very valuable to advertisers. When customers use long-tail keywords, it is a good indication that they are ready to buy the item for which they are searching. Purchasing long-tail keywords in pay-per-click advertising for the products or services available on a particular site enables the site owners to draw customers who are looking specifically for what they offer. This targeted, contextual advertising is much more likely to result in a sale than random ad placement.
For example, a person searching for sectional sofas is quite likely to be just browsing. When a customer gets very specific – like searching for a white leather reclining sectional sofa -- it is more likely that they know what they want and are ready to buy. vendors, especially those specializing in niche products, are advised to find keyword phrases that a customer is likely to use when searching for the products or types of products they offer. Model numbers, colors and unique options are a few things to keep in mind for keyword selection. In this way, vendors can target customers that want what they have, when they are ready to buy.
In pay-per-click advertising, long-tail keywords are less expensive to buy and result in more purchases per click than popular short keywords, which bring more traffic but result in fewer purchases. The most searched keywords may boost a site's visibility somewhat, but it is hard to rank well in these terms. Popular keywords will come with a greater cost and may not bring much increase in sales. Long-tail keywords are easier to rank well on, cost less and result in more sales.