The marriage between Physics and Mathematics is possible by the intermediary of Geometry and Topology. Geometrical and topological concepts permeate the whole mathematical description in physical theories. This is a natural consequence of the fact that physical phenomena arise in Space and Time. Balance equations are the most important physical equations. We remember the balance of mass, the momentum, the angular momentum, the energy, the entropy, the electric charge, the particle number, etc. A balance law states that given a space region and a time interval the amount of a given physical variable produced inside the space region in the time interval is equal to the sum of two quantities. The one is the amount of the same physical variable stored inside the region. The other is the amount of the physical variable outflowed across the boundary of the region in the same interval. A particular case of balance arises when production vanishes: in this case balance law is reduced to a conservation law.