It has to do with the overall spin. Bosons have integer spin $(0, 1, 2, \dots)$ and fermions have half-integer spin $(n+\tfrac{1}{2})$.

They can be either elementary or composite. Fundamental fermions that we discovered so far are the quarks and the leptons of the Standard Model. Fundamental bosons that we discovered so far are the gauge bosons (gluons, photon, $W^{\pm}$, $Z^{0}$) and the Higgs boson.

Composite particles like baryons are fermions because they are made of three quarks. Mesons are bosons because they are made of two quarks. Protons and neutrons are baryons and therefore are fermions. A nucleus composed of an odd number of nucleons it is a fermion, and if it is composed of an even number of nucleons it is a boson. For example, Helium-3 is a fermion and Helium-4 is a boson.

It has to do with the overall spin. Bosons have integer spin $(0, 1, 2, \dots)$ and fermions have half-integer spin $(n+\tfrac{1}{2})$.

They can be either elementary or composite. Fundamental fermions that we discovered so far are the quarks and the leptons of the Standard Model. Fundamental bosons that we discovered so far are the gauge bosons (gluons, photon, $W^{\pm}$, $Z^{0}$) and the Higgs boson.

Composite particles like baryons are fermions because they are made of three quarks. Mesons are bosons because they are made of two quarks. Protons and neutrons are baryons and therefore are fermions. A nucleus composed of an odd number of nucleons is a fermion, and if it is composed of an even number of nucleons it is a boson. For example, Helium-3 is a fermion and Helium-4 is a boson.