A Long-Tail Keyword is a key phrase that consists of three or more words. It is used in contrast to “Short-Tail Keywords”, which consist of just one or two keywords.
Generally speaking, the shorter the keyword or key phrase, the higher the search volume. That means that Long-Tail Keywords tend to be searched less on search engines – but they’re keyed into search engines in order to locate specific websites, businesses, products, or services. As such, Long-Tail Keywords are regarded as useful if a website is attempting to attract niche traffic.
The term “Long-Tail” refers to a search volume graph, which shows that the more keywords you add to a key phrase, eventually the search volume will level out and the addition of more keywords will have little impact on search volume.