The term matter includes anything that takes up space and has a defined mass. Matter essentially includes all living and nonliving items that have a physical presence: humans, hay bales, butterflies and baseball bats are all classified as matter. In contrast, energy, light, sound, thoughts and emotions are not considered matter.
All items classified as having matter contain mass and weight. Mass refers to the quantity of matter that an object contains. However, mass is not to be confused with weight, which is a strong force generated by the force of gravity, or gravitational attraction, that pulls on an object. Mass is a basic property of an object that does not depend on that object's location. In addition to having common characteristics of mass and weight, all kinds of matter come in one of three forms: solids, liquids and gases. Solids are defined, structured and right and have fixed shapes and volumes. Rocks, tables and lamps are all examples of solids. Liquids, in contrast, have defined volumes but take the shape of their containers: consider, for instance, the way water molds to the shape of a drinking glass or sits in a vase. Lastly, gases have neither fixed volumes nor shapes; they expand and rise to fill containers and spaces.