Flapping wings became a primary source of inspiration for research into Micro Air Vehicles (MAVs), Unmanned Aerial Vehicles (UAVs) etc. For practical applications, the flapping wing has to adapt the morphology and kinematics that match the dynamical features of fluids to attain efficient propulsion. The book describes numerical investigations on a teardrop-shaped airfoil and wing performing different flapping oscillations. Pitching, heaving and the combined motion of pitch and heave are the different flapping oscillations investigated. A uniform, laminar, incompressible flow is considered over the airfoil and wing while performing the flapping oscillations. The influence of flapping frequency and amplitude on the wake characteristics behind the flapping airfoil are discussed. The force experienced by the flapping wing depends on the vortex structures and their evolution. The identification of vortex formation, their interactions and separation from the wing surface are necessary to understand the force experienced by the wing. The influence of aspect ratio on the formation and evolution of vortex structures is relevant in developing practical applications.