In the past few decades, algebra had witnessed subtle developments. In this book the authors have embarked upon exploring two important notions- the dimension theory and homology theory. With the advent of notion of dimension of a ring (the Krull dimension), algebraists could unify certain topological and algebraic notion albeit under restrictions. Thus while on one side the algebraic theories were shaping up venturing into the territories of topology, on the other side of it, researchers delved into the regime of homology to gain insight about geometry. What panned out was the rich theory of projective, injective and flat modules.In the present book, we attempt to provide an account of the theories laid down in the above paragraphs based on our own endeavour.