The provided source is an extensive excerpt from a Wikipedia article focusing on the life and intellectual contributions of Karl Marx. It offers a structured overview of his biography, detailing his childhood, education at the universities of Bonn and Berlin, and significant phases of his life spent in Paris, Brussels, Cologne, and London. Crucially, the text outlines the development of his thought, emphasizing influences like Hegelianism and French socialism, and defining his key concepts such as historical materialism, class struggle, alienation, and his critique of political economy, culminating in works like Das Kapital and The Communist Manifesto. Finally, the source addresses his legacy, noting his profound impact on modern sociology, political movements, and various schools of Marxist thought globally.