The paper discusses the light-cone quantization of gauge theories, focusing on its applications in hadron physics and quantum field theory. The authors highlight the unique features of light-cone quantization, such as the ground state of the free theory being the same as the full theory's ground state. They explore two perspectives: using light-cone quantization to represent hadrons as relativistic bound states of quarks and gluons, and employing it as a computational tool for simulating quantum field theories on computers. The light-cone Fock state expansion of wavefunctions provides a precise definition of the parton model and a general calculus for hadronic matrix elements. The paper presents new applications, including calculations of exclusive weak decays of heavy hadrons and intrinsic heavy-quark contributions to structure functions. It also outlines a general non-perturbative method, "discretized light-cone quantization," which is invariant under large classes of light-cone Lorentz transformations and can be formulated with ultraviolet regularization independent of momentum space discretization. The authors discuss the construction of the light-cone Fock basis, the structure of the light-cone vacuum, and renormalization techniques required for solving gauge theories within the Hamiltonian formalism on the light cone.The paper discusses the light-cone quantization of gauge theories, focusing on its applications in hadron physics and quantum field theory. The authors highlight the unique features of light-cone quantization, such as the ground state of the free theory being the same as the full theory's ground state. They explore two perspectives: using light-cone quantization to represent hadrons as relativistic bound states of quarks and gluons, and employing it as a computational tool for simulating quantum field theories on computers. The light-cone Fock state expansion of wavefunctions provides a precise definition of the parton model and a general calculus for hadronic matrix elements. The paper presents new applications, including calculations of exclusive weak decays of heavy hadrons and intrinsic heavy-quark contributions to structure functions. It also outlines a general non-perturbative method, "discretized light-cone quantization," which is invariant under large classes of light-cone Lorentz transformations and can be formulated with ultraviolet regularization independent of momentum space discretization. The authors discuss the construction of the light-cone Fock basis, the structure of the light-cone vacuum, and renormalization techniques required for solving gauge theories within the Hamiltonian formalism on the light cone.