Most forms of matter are built from very many tiny particles. What are these particles called?

1. A brick wall is built from very many identical bricks stacked together. 2. Matter works in the same way, because it is made of very many small particles. 3. Those small particles are called atoms, and they are far too small to see. _Source: Siyavula Natural Sciences Grade 8 (CC BY 4.0), The building blocks of matter_