Wilson’s two papers lay the foundations for the renormalization group approach, which is a mathematical framework for studying the properties of a system on various length scales. As a system makes a phase transition, the length scale over which correlations extend becomes infinite, and the renormalization group provides a powerful way to describe the correlations.
What is renormalization:
In theoretical physics, the renormalization group (RG) refers to a mathematical apparatus that allows systematic investigation of the changes of a physical system as viewed at different scales. In particle physics, it reflects the changes in the underlying force laws (codified in a quantum field theory) as the energy scale at which physical processes occur varies, energy/momentum and resolution distance scales being effectively conjugate under the uncertainty principle (cf. Compton wavelength).
use renormalization in quantum electrodynamics:
