Here is one of those things that sneaks up on you and then just changes the whole damn world. Chris Anderson's article in Wired magazine is the best I've ever seen on the economics of the entertainment industry, including concrete reasons why we're saddled with the likes of Ashlee Simpson.
The "long tail" refers to the shape of the graph of the quantity of success of a thing (a book or a movie or a record etc.) vs. its rank in the popularity pecking order. It looks like this (from Chris's blog):
That big spike at the front represents the megahits. In music, these are the records at the top of the Billboard chart. The Y axis represents how many copies they sold. The long tail is the area in yellow. This is the obscure stuff. But the significant thing is that there is at least some audience for it. In an age when production costs are plunging, and distribution costs are approaching zero, this means the market for niche products will soon be larger than the market for hits. Not only is this a major disruptive phenomenon for life as we know it, it is wonderful news to these tired ears.
When people ask me what kind of success I want for my band I always tell them, "I want to reach all the people who stand a chance of loving it." The concept of the long tail articulates this beautifully. There are potentially a lot of people buying their records in the "red zone" who would really be into our music. We stand a fighting chance of coaxing them down the curve over to where we are.