Quantum field theories are quite difficult. The successes achieved by using quantum field theories are rather limited because in these theories one faces various difficulties. Later Dirac introduced an alternative process to quantize the fields. He introduced Hamiltonian equations of motion from Lagrangian to describe the laws of mechanics and gravitation. It has wide application in classical mechanics, quantum mechanics and quantum field theory, as well as in general relativity etc. One may deal with Hamiltonian in general frameworks as well as oscillatory systems.