This chapter introduces the formulation and application of lattice field theory as a powerful, non-perturbative approach to quantum field theory. The formalism is built on the Euclidean path integral, drawing a formal connection to statistical mechanics. The text details the numerical discretization of scalar and fermionic field theories, covering key challenges such as maintaining gauge invariance through link variables and mitigating the fermion doubling problem. Solutions to fermion doubling, including Wilson fermions and staggered fermions, are discussed. Furthermore, the chapter outlines the use of Monte-Carlo integration for calculating observables, such as the hadron spectrum and the static quark-antiquark potential from Wilson loops. Crucially, it emphasizes the necessary process of extrapolating results to the continuum limit to extract physical predictions.