Physical entities refer to tangible objects that occupy space and have mass. These can range from everyday items like books and chairs to larger structures such as buildings and vehicles. They are distinct from abstract concepts, as physical entities can be perceived through the senses. In the realm of science, physical entities are crucial for understanding the laws of physics and chemistry. They interact with one another and can undergo changes, such as melting or combustion. This interaction forms the basis of many scientific principles and helps us comprehend the material world around us.