abstract: A short review of different formulations of Morse theory on finite dimensional, compact manifolds will be reported, with a focus on the Harvey-Lawson finite volume approach. A generalization of Morse Theory on non compact manifolds will then be presented; the Morse function is not assumed proper (nor PS), yet a weakly proper condition is required. In contrast to the compact case, here the different possible approaches will lead to quite different capabilities of the theory. If time permits, applications to the dynamics of gradient systems arising in Novikov theory (where the morse function are usually not PS), and to some functional analytic questions about complexes of differential forms, will show the utility and naturality of the generalized Morse theory.