Definition 7.2.2. Let $\mathcal{C}$, $\mathcal{A}$ be categories. A presheaf $\mathcal{F}$ on $\mathcal{C}$ with values in $\mathcal{A}$ is a contravariant functor from $\mathcal{C}$ to $\mathcal{A}$, i.e., $\mathcal{F} : \mathcal{C}^{opp} \to \mathcal{A}$. A morphism of presheaves $\mathcal{F} \to \mathcal{G}$ on $\mathcal{C}$ with values in $\mathcal{A}$ is a transformation of functors from $\mathcal{F}$ to $\mathcal{G}$.

Comment #1016 by correction_bot on

Isn't $\mathcal{C}^{opp}$ the stacks project's notation for the opposite category?

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