The existence of a relationship between the inertial and gravitational mass of an object is evident from the fact that they have same the value. However General Relativity shows that inertial and gravitational mass are two aspects of the same thing. Special Relativity shows that an objects mass is equivalent to the amount of energy an object contains.
Normal Matter is composed of atoms. Atoms are a nucleus; made of protons and neutrons; with electrons around it. This form of matter in what we commonly experience. Matter makes up everything around us, everything we see, everything we touch and even our bodies. Matter is one of the three main parts of the Universe Space, Time and
(matter) Relativity shows them to be inter-related in that space and time are so interrelated that they form a single entity called space-time. Furthermore mass warps space-time forming gravity and the motion of mass contracts both space and time. In common experience matter is what makes up objects around us and Physics has shown that it to be a lot more. Matter is a fundamental part of the universe. Mass.