What is matter?

Answer by  fellwanderer (146)

Normal particles are made up of a nucleus of protons and neutrons and are surrounded by a cloud of electrons. Anti matter is made up of different particles: positrons (anti-electrons), anti-neutrons and anti-protons. The difference between the neutron and the anti-neutron is that they have opposite spin. Electrons (protons) differ from positrons (anti-protons): they have opposite spin and charge.

Answer by  john11 (617)

classically, matter was defined as that which has mass. Anything that has mass has inertia, and this is shown by the formula F = m*a. Here you can view m as mass and F as inertia (force). Einstein later showed that mass and energy are equivalent by E = m*c^2; That is I can convert energy in to mass.