Molecules and the process of star formation

Abstract
Stars are born inside clouds of gas and dust which are predominantly molecular in composition. The chemistry and physics of these molecules are important contrib- utors to the overall evolution of the parent clouds and on the formation of the stellar systems. We review the methods and techniques through which molecules are used to probe the process of star formation. We also detail our current understanding of the chemical processes active in molecular clouds preceding and during the initial stages of stellar birth.