Singularly perturbed boundary-value problems(SPP) arise in several branches of engineering and applied mathematics where the edge effects are important. These problems are often described by differential equations where the highest order derivative is multiplied by an arbitrarily small parameter`?`known as the singular perturbation parameter. The solution of these problems possesses boundary (or interior) layers which are thin narrow regions in the neighborhood of the boundary (or interior) of the domain, where the gradient of the solution becomes very high as ? goes to zero. Classical numerical schemes fails to yield satisfactory numerical approximations on uniform grids due to the presence of boundary layers. To solve SPP, fitted mesh methods are often followed which comprise of standard finite difference operators on specially designed meshes. The aim of this book revolves around developing, analyzing and optimizing the ?-uniform upwind based fitted mesh methods resolving the convection-dominated layer type problems using non uniform grids.