The long-tail effect refers to the concept that the aggregate of less popular items can rival or exceed the sales of the most popular items, especially in online markets. For example, let’s consider an online music streaming service. The most popular songs (the “hits”) make up a significant portion of the total streams. However, the combined streams of all the less popular songs (the “long tail”) can equal or even exceed the streams of the hits. This is the long-tail effect in action.