A particle is a small localized object that can be ascribed physical properties such as volume or mass. In physics, particles are often classified into categories like subatomic particles, which include protons, neutrons, and electrons. These particles are the building blocks of matter and play a crucial role in the universe's structure. Particles can also refer to elementary particles, which are not made up of smaller components. Examples include quarks and leptons. Understanding particles is essential for comprehending fundamental forces and interactions in the universe, making them a key focus in fields like quantum mechanics and particle physics.