A brief introduction to some of the ideas of a gauge theory are presented w
ith a review of the role of the path integral in developing a quantum theor
y as well as the path integral over a space of the form S/G. The path integ
ral of the gauge-invariant function over the space of inequivalent connecti
ons under a given measure is discussed. It is shown that by taking the Yang
-Mills Lagrangian, a formal quantum mechanical Hamiltonian in the space of
gauge-invariant functionals can be derived. The scaler product is then give
n by the formal Riemannian volume element on the space of orbits.