Dialectics is a philosophy that explains change, motion, and development. In this respect, Hegel's ideas provided a profound leap from the mechanical and rigid outlook of those who preceded him.
Hegel's dialectics were the basis for the revolutionary philosophy of Marxism - dialectical materialism. But in order to make sense of Hegel, Marx and Engels had to turn him upside down, taking his philosophy from the realm of idealism to that of materialism.
With this method, Marx revolutionised philosophy, history, and economics, providing the tools with which we can not only interpret the world, but fundamentally change it.