A long tail keyword is a keyword string that is “longer”. The question of “How long does it have to be?” is up to debate, however, one thing it is definitely not is a single word keyword. A longer tail keyword often has a reduced amount of traffic but a higher amount of relevance for an advertiser, should it pertain to their business. The opposite of a Long Tail Keyword is a – you guessed it – a short tail keyword but there is certainly some gray area.