What do we mean by fundamental …

Fundamental particles it means that smallest particle of the atom. Nowadays there are three fundamental particles are present in the nature that is proton electron and neutron but the smallest particle which is also present in the world that is quark. The quirk divided into two part first part is upward quark and the second part is down quark. Its value is plus 2e/3 and -e/3 respectively.

Fundamental particles are electrons, protons, neutrons and photons

In particle physics, an elementary particle or fundamental particle is a subatomic particle with no sub structure, i.e. it is not composed of other particles. Particles currently thought to be elementary include the fundamental fermions (quarks, leptons, antiquarks, and antileptons), which generally are "matter particles" and "antimatter particles", as well as the fundamental bosons (gauge bosons and the Higgs boson), which generally are "force particles" that mediate interactions among fermions. A particle containing two or more elementary particles is called a composite particle. Ordinary matter is composed of atoms, once presumed to be elementary particles-atom meaning "unable to cut" in Greek-although the atom's existence remained controversial until about 1910, as some leading physicists regarded molecules as mathematical illusions, and matter as ultimately composed of energy. 11/12 Subatomic constituents of the atom were identified in the early 1930s; the electron and the proton, along with the photon, the particle of electromagnetic radiation.l11 At that time, the recent advent of quantum mechanics was radically altering the conception of particles, as a single particle cloud seemingly span a field as would a wave, a paradox still eluding satisfactory explanation.