Long Tail

Definition

The long tail is the large number of niche items that individually sell little but together account for a significant share of sales. It describes markets, usually online, where shelf space is cheap and sales follow a heavy-tailed distribution rather than stopping at a sharp cut-off.

In plain terms

A physical shop stocks the hits; an online catalogue can list almost everything. The sales curve then has a “head” of a few big sellers and a long “tail” of items with a few sales each. The idea was popularised by Chris Anderson in 2004; later studies showed the real balance between hit and tail varies by market, and many tail items sell nothing at all.

For measurement the point is coverage: a list of the top sellers describes the head. What is in the tail, and how much it matters, is invisible unless you collect it on purpose.

Example

Using the synthetic model from Power-law Distribution (the item at rank k sells 1,000 / k a day), 1,000 items in total:

The 990 tail items outsell the ten best sellers, but each tail item sells very little, so any one of them is hard to measure and easy to overlook.

Common misunderstandings

• “The tail is worthless.” Together it can be the larger part of sales, even though each item is small.
• “Everything in the tail sells.” Many items sell nothing in a given period.
• “The tail is always growing.” Whether hits or niches gain share depends on the market and the period.