  Differential structure of lattices can be defined if the lattices are treated
as models of noncommutative geometry. The detailed construction consists of
specifying a generalized Dirac operator and a wedge product. Gauge potential
and field strength tensor can be defined based on this differential structure.
When an inner product is specified for differential forms, classical action can
be deduced for lattice gauge fields. Besides the familiar Wilson action being
recovered, an additional term, related to the non-unitarity of link variables
and loops spanning no area, emerges.
