Long-Tail Keyword

A long-tail keyword is a specific search phrase of three or more words — not "running shoe" but "trail running shoe waterproof men 44".

Long-tail keywords have lower search volume but significantly higher purchase intent: someone searching that specifically knows exactly what they want. Competition is often a fraction of what the head term has.

The rule of thumb for Amazon listings: head keyword in the title, long-tail variations in bullet points and backend search terms. That way you catch both the main search and the niche queries without cramming the title.