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The Complement of Knots and Links in codimension 2 have many covering spaces and their homology groups be come modules over rings like A =Z [t, t^-1] or A_n = Z [t₁ , ..., t_n, T₁^-1, ... t_n^-1]. The study of these rings and modules are then ve ry important because manyinvariantsof the Knots and Lin ks are defined through these modules. The pourpose of this work is to collect and de velop properties of these rings and modules, find 'some re lationship betwen them and give some examples.