Atomism is a philosophical theory that suggests everything in the universe is made up of small, indivisible particles called atoms. This idea dates back to ancient Greek philosophers like Democritus and Leucippus, who proposed that these tiny particles combine in various ways to form all matter. Atomism helps explain the nature of physical substances and their interactions. In modern science, atomism has evolved into the field of atomic theory, which is foundational to chemistry and physics. This theory describes how atoms bond together to create molecules and how they behave in different states of matter. Understanding atomism is crucial for advancements in various scientific disciplines.