Postmodernism is a complex movement in art, science, and literature that emerged in the late 20th century, characterized by its rejection of absolute truths and emphasis on relative perspectives, equality, and internationalism. It was notably championed by figures like Jean-François Lyotard and Andy Warhol, who challenged the conventions of modernism. Key aspects include the belief that all artworks are valid, truth is subjective, and traditional moral and religious systems are not objectively superior.