A chemist is a scientist who studies matter: what things are made of, how they behave, and how they change when combined with other substances. Chemists might investigate why iron rusts, how soap cleans, or what makes bread dough rise. They work in laboratories, mixing substances, heating them, cooling them, and observing what happens.

Some chemists develop new medicines to fight diseases. Others create stronger plastics, longer-lasting batteries, or better fertilizers to help crops grow. A chemist might figure out how to remove pollution from water or invent a new flavor of artificial sweetener. The shampoo you use, the gasoline that powers cars, and the lithium-ion battery in your tablet all exist because chemists figured out how to make them.

In British English, chemist can also mean a pharmacist or a pharmacy. When someone in London says “I'm going to the chemist,” they mean the drugstore where they pick up prescriptions and buy medicine.

The word connects to chemistry, the science chemists practice. Chemistry explains the physical world at the level of atoms and molecules, the tiny building blocks that make up everything around you. When you understand chemistry, you understand why vinegar and baking soda fizz, why silver tarnishes, and why cut apples turn brown.