Mesh

Mesh
is an option for Plot that specifies the mesh to be drawn. The default is Mesh->None.

>>DensityPlot[Sin[x y], {x, -2, 2}, {y, -2, 2}, Mesh->Full] = -Graphics-

>>Plot3D[Sin[x y], {x, -2, 2}, {y, -2, 2}, Mesh->Full] = -Graphics3D-