This work addresses the topics of: what turbulence is and how, why and where it occurs, the mathematical equipment used for the representation and study of turbulence; continuum equations used for the analysis of turbulence; ensemble, time and space averages as they are applied to turbulent quantities; and Fourier analysis and the spectral form of the continuum equations. This text also concerns itself with weak or moderately weak turbulence to explain the nature of turbulence, since processes that occur in weak turbulent flow are the same as in strong flow.