The term long tail refers to the ability of online sellers to offer a very broad and deep
product range. This contrasts with stationary sales formats, which have to focus on fast-turnaround items due to space constraints and for profitability reasons. The term long-tail is derived from the long list of orderable items that can be stocked and offered at a relatively low cost. Whereas the product range of a traditional retail store amounts to a few hundred or a few thousand products, the range of online providers can consist of several million products. Even if exotic products are only sold in small quantities, these products cannot be marketed via traditional retail outlets for cost reasons.
Examples of online shops are the iTunes Store, which offers millions of different music tracks for download, or Amazon with a very broad and deep range of goods that cannot be reproduced by any stationary department store.