An Introduction to Molecular Clouds describes the formation of molecular clouds and the innovative features of molecular clouds with different physical parameters. In this book, Jean-gravitational instability is discussed with different physical parameters, which is the major cause of the formation of molecular clouds in the interstellar medium (ISM), and the way molecular clouds are formed in the astrophysical plasma environment is described. The authors aim to determine the basic conditions responsible for the formation of heavenly bodies in the universe. The book deals with radiative instability in a variety of conditions incorporating different physical parameters such as viscosity, rotation, permeability, porosity, thermal conductivity, Hall current, Finite ion Larmor radius corrections, finite electrical resistivity, radiative heat-loss functions and finite electron inertia, both in gaseous plasma and quantum plasma environments.