Proposition 7.7.
The category \(\Sch_{\Zar}^{\et}\) is (up to size issues) a topos. In fact, there is an equivalence
\[\Sch_{\Zar}^{\et} \simeq \Shv_{\Zar}(\CRing^{\ad,\op}),\]
where \(\CRing^{\ad}\) is the wide subcategory of \(\CRing\) spanned by the localization maps of the form \(R \to R[s^{-1}]\).