In more detail
The name comes from the shape of a chart of search demand. A small number of broad terms ("shoes", "insurance") attract very large volumes, forming the "head". A huge number of specific phrases each attract only a few searches, forming a long, thin "tail". Individually small, these specific searches add up.
Long-tail searches tend to have clearer intent. Someone searching "emergency boiler repair Sunday Manchester" knows exactly what they want. That specificity often means higher conversion rates and less competition, because fewer sites target the exact phrase.
Search engines are good at understanding language, so you rarely need a separate page for every long-tail variation. A thorough page that covers a topic well can rank for hundreds of related phrases. Google's SEO starter guide advises writing naturally for readers and not worrying about including every keyword variation.
Search Console's Performance report is the best place to find the long-tail queries you already appear for. Many will have only a handful of impressions each.
Why it matters when hiring an agency
A sensible keyword strategy usually includes long-tail searches because they can deliver results sooner than competitive head terms. They're also the easiest way to make a ranking report look impressive. An agency can show page-one rankings for obscure phrases that nobody searches.
When reviewing a keyword plan or a "guaranteed rankings" offer, check that the long-tail terms are real searches that relate to what you sell. Our guide to spotting fake SEO guarantees explains how keyword choice can disguise weak results.