This is an atom, and it is very small. Atoms are made up of particles. Red circles represent protons and blue circles represent neutrons. The atom shown here is a helium atom.

A particle is a tiny bit of matter that makes up everything in the universe. In particle physics, an elementary particle is a particle which cannot be split up into smaller pieces.

There are many different types of particles, with different particle sizes and properties.

Macroscopic particles are particles that are larger than atoms or molecules. They have volume and shape. Powder and dust are some examples of macroscopic particles. Nanoparticles are an intermediate size, being a very fine powder but much larger than atoms.