Final answer:
Liquids take the shape of the bottom of their container, while gases take the shape of their entire container. Liquids have definite volumes but their shape changes based on the container, while gases neither have definite shape nor volume and fill their container. Both liquids and gases are considered to be fluids.
Step-by-step explanation:
Liquids and gases are considered to be fluids because they yield to shearing forces, whereas solids resist them. Like solids, the molecules in a liquid are bonded to neighbouring molecules but possess many fewer of these bonds. The molecules in a liquid are not locked in place and can move with respect to each other. The distance between molecules is similar to the distances in a solid, and so liquids have definite volumes, but the shape of a liquid changes, depending on the shape of its container. Gases are not bonded to neighbouring atoms and can have large separations between molecules. Gases have neither specific shapes nor definite volumes since their molecules move to fill the container in which they are held.