Read full 9 page article by Dave Chaffey

The phenomenon was first noticed by George Kingsley Zipf, professor of linguistics at Harvard who observed this phenomenon in word usage. Zipf’s law refers to any large collection of items ordered by size of popularity. It shows how the frequency or popularity of the items declines.

Zipf’s law states that if in a large collection ordered or ranked by popularity, the second item will be around half the popularity of the first one and the third item will be about a third of the popularity of the first one.

In general:

The kth item is 1/k the popularity of the first.

Implications for marketers

Zipf’s law can be applied to describe the exponential decrease in preferences for using, selecting or purchasing from a choice of items.

Since the tail is long, it is a mistake to concentrate marketing efforts only on the most popular items since many customers or prospects will have a different behaviour and will have different content or product preferences.

Areas of digital marketing where the long-tail phenonmenon is apparent include:

• The popularity of search terms within a category or for an individual site.
• The popularity of content within a web site.
• The popularity of web sites in a category measured through unique visitors
• Response to an e-mail campaign through time

Read more about the implications of Zipf's law for marketers at the end of my article on Fundamental digital laws.

Read Wired original

Chris Anderson now has a blog site, the long tail to support a book on the topic to be published early in early 2006.

Read Guardian version