Leucippus was an ancient Greek philosopher, often credited as one of the founders of atomism. He lived around the 5th century BCE and is known for proposing that everything in the universe is made up of tiny, indivisible particles called atoms. This idea was revolutionary for its time, as it suggested that matter is not continuous but rather composed of discrete units. Although not much of his work survives, Leucippus influenced later philosophers, particularly Democritus, who expanded on his ideas. Together, they laid the groundwork for the atomic theory, which has become a fundamental concept in modern science, shaping our understanding of matter and the physical world.