An analysis is made on the gauge concept, global and local, illustrating the most important aspects on the way to proceed for the establishment of the gauge symmetry in classical electrodynamics, quantum mechanics and quantum electrodynamics, showing how the gauge symmetry produces a result that is physically significant. Under this context, the gauge concept is implemented using the Lagrangian formalism and demanding its invariance under a symmetry group. In addition, the ideas of Yang and Mills supported by the non-Abelian group SU (2) are embroidered as a first explanation about the dynamics of the interaction between the proton and the neutron from the conservation of the isospin. This analysis reveals how the gauge concept becomes a pa...