A particle is a tiny piece of something, often so small you can barely see it or can't see it at all. When you clap two chalkboard erasers together, you see a cloud of chalk particles floating in the air. Each speck of dust dancing in a sunbeam is a particle. Sand is made of rock particles. Flour, salt, and sugar are all made of particles of different sizes.

Scientists use the word particle to describe the incredibly tiny building blocks that make up everything in the universe. Atoms are particles, and atoms themselves contain even smaller particles like protons, neutrons, and electrons. These particles are so small that millions of them could fit on the period at the end of this sentence.

The word can also describe bits of language. In grammar, a particle is a small word like “up” in “look up” or “to” in “going to.” These little words don't change form but help give meaning to other words.

When something breaks into particles, it shatters or crumbles into many tiny pieces. Particle board is made by pressing wood particles together with glue. Understanding particles helps scientists explain how matter works, from the dust under your bed to the stars in space.