A formulation of gauge theories in which space and time are taken to be discrete, rather than continuous. At the end of calculations in lattice gauge theories it is necessary to take the continuum limit. Lattice gauge theory is used to make calculations for gauge theories with strong coupling, such as quantum chromodynamics, in which many of the important features of the theory cannot be obtained by perturbation theory. Lattice gauge theory is particularly suitable for numerical and computational calculations. Techniques from statistical mechanics can be used in lattice gauge theory. Difficulties arise with putting fermions on a lattice, although various remedies have been used to overcome these difficulties.