path integral in quantum field theories

Introduction/purpose: starting from the hamiltonian an alternative description of quantum mechanics has been given, based on the sum of all possible paths between an initial and a final point. methods: theoretical methods of mathematical physics. integral method based on the path integral. results: the method and concepts of the path integral could be applied to other branches of physics, not limited to quantum mechanics. conclusions: the path integral approach gives a global description of fields, unlike the usual lagrangian approach which is a local description of fields.