Which states of matter have a definite volume why do they keep the same volume?

The states of matter with a definite volume are solids and liquids. Solids maintain a fixed volume due to their closely packed particles that vibrate in place, preventing any change in shape or volume. Liquids also have a definite volume because their particles are close together but can move past one another, allowing them to take the shape of their container while retaining a consistent volume. The intermolecular forces in both states prevent significant expansion or compression, ensuring volume stability.