Market segmentation is the process of grouping a market into smaller subgroups. This is not something that is arbitrarily imposed on society: it is derived from the recognition that the total market is often made up of submarkets (called segments). These segments are homogeneous within (i.e. people in the segment are similar to each other in their attitudes about certain variables). Because of this intra-group similarity, they are likely to respond somewhat similarly to a given marketing strategy. That is, they are likely to have similar feelings about a marketing mix comprised of a given product, sold at a given price, distributed in a certain way, and promoted in a certain way.
Where a monopoly exists, the price of a product is likely to be higher than in a competitive market and the quantity sold less, generating monopoly profits for the seller. These profits can be increased further if the market can be segmented with different prices charged to different segements (referred to as price discrimination), charging higher prices to those segments willing and able to pay more and charging less to those whose demand is price elastic. The price discriminator might need to create rate fences that will prevent members of a higher price segment from purchasing at the prices available to members of a lower price segment. This behaviour is rational on the part of the monopolist, but is often seen by competition authorities as an abuse of a monopoly position, whether or not the monopoly itself is sanctioned.
