We use the term matter as a general word for scientific “stuff.” By matter we mean atoms, elements, particles, dust, gases, rocks, minerals, and their various combinations.
The basic scientific definition of matter is something that has mass and takes up space. Using matter as a general word is helpful because specifically naming the components that make up the raw material of Earth or the universe would get complicated.
Reading this would be very difficult, except for a scientist. When practical or pertinent, more specific names are used and explained.