Matter is anything that has mass and takes up space (has volume). Everyday solids and liquids clearly qualify; gases do too, even when they are hard to see, because air still has measurable mass and occupies volume.
All ordinary matter is built from a limited set of building blocks called atoms. Scientists have identified 118 types of atoms (elements). Atoms often bond into molecules—groups of two or more atoms—whose arrangements create the huge variety of materials we encounter, from water and air to rocks and living tissue.