As high street and main street businesses continue to suffer, there's a new rule in business: forget about the general audience and instead stake out an identifiable niche.Woolworths suffered from a lack of identity and found that low quality and low price wasn't enough; General Motors crashed as motorists failed to distinguish between cars in their range. Yet HBO, Moleskine and specialist media like The Economist have all succeeded by building their authority over narrow areas of expertise and cultivating a passionate following - and their profits have mushroomed. Fascinating and thought-provoking, Niche is a superb examination of how innovation and profitability are moving to a series of tightly defined but globally scattered niches, bound together by the reach of the net.