A situation where a monopolist sells different units of output at different prices. There are different degrees of price discrimination. For example, with third-degree price discrimination a different price is charged in each market. For maximum profit a monopolist sets prices so that at the amounts sold, marginal revenue in each market equals marginal cost. If the elasticity of demand differs across markets, the profit-maximizing price will be higher in markets with less elastic demand, and lower in markets with more elastic demand. Discriminating monopoly is only possible when the monopolist can identify which market each customer belongs to, and where resale between markets is costly or impossible.