Karl Marx was the greatest critic of capitalism, yet his ideas are widely dismissed or misunderstood. But understanding Marx is indispensable for anyone who wants to grasp why capitalism is a system of exploitation, instability and repeated crises. Joseph Choonara here introduces readers to some crucial Marxist approaches - as developed above all in the three volumes of Capital. He also outlines how this can be applied to capitalism as it has developed since the 19th century.