What is matter?

Matter is defined as anything that has mass and occupies space. This includes all physical substances around us, regardless of their state (solid, liquid, or gas). Everything that we can touch or perceive in our environment is considered matter because it is made up of particles that possess mass and volume. This foundational concept in science helps to differentiate matter from energy and other entities.

The other concepts provided don't fully encapsulate the definition of matter. For instance, while energy is a crucial aspect of physical processes, it is not classified as matter because it does not have mass or occupy space in the way that matter does. Furthermore, the idea that only solid objects constitute matter is too restrictive, as liquids and gases also qualify as matter. Lastly, defining matter strictly as visible substances excludes many forms of matter, such as gases or microscopic particles, which, although invisible to the naked eye, still possess mass and occupy space.