The name ``density theorem’’ refers to a second formulation of this result, which asserts that the representable functors form a dense subcategory of the presheaf category $\textup{\textsf{cat}}^{\mathsf{C}^\mathrm{op}}$. Informally speaking, a subcategory is dense if any object in the larger category is a colimit of a diagram valued in the subcategory. The precise meaning is given by the statement of the following theorem: