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The category of functors from $C$ to $D$, denoted $\mathcal{D}^\mathcal{C}$, is a category where the objects are the functors from $C$ to $D$, and the morphisms are the natural transformations between these functors.

Conditions: $C$ and $D$ are categories.

The category of functors from $C$ to $D$, denoted $\mathcal{D}^\mathcal{C}$, is a category where the objects are the functors from $C$ to $D$, and the morphisms are the natural transformations between these functors.

Conditions: $C$ and $D$ are categories.