When you break things down into the smallest possible particles, you get elementary particles. These include electrons, quarks (the things that make up protons/neutrons), and photons.
These can be classified into two groups: fermions and bosons. Fermions include quarks, electrons, and neutrinos. Bosons include photons (electromagnetic force carriers), gluons (strong force), W & Z bosons (weak force), and gravitons (gravity)
The main difference between the two groups is a property called “spin”. Fermions half spins of 1/2, 3/2, -1/2, etc. Bosons have spin -1, 0, 1, 2, etc. Fermions, with their half-integer spin, obey the Pauli Exclusion Principle, which says you can’t have 2 particles in the same place at the same time. Bosons don’t obey this rule, meaning you can cram as many of them into the same place as you want
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