Substances are around us everywhere. The food we eat, the air we breathe, the chair we sit on, the perfume we use - all of that is made of different substances. Chemistry learns substances, their properties and transformations. What substances are harmful? How to avoid poisoning? How can we analyze substances and their behavior? What do the properties of substances depend on? How quality control of food, drinks, medicines, environmental objects is provided? How can we synthesize new substances? Chemistry gives us the answers for all these questions.