Let $k$ be a field, let $k_s$ denote its separable closure.

The functor

$\begin{cases}
k.Sch_{et}\to Gal(k_s / k)- Mod
\\
X\mapsto X(k_s)
\end{cases}$

from étale k-schemes? to the category of Galois modules$Gal(k_s/s)-Mod$ is an equivalence of categories. Here $Gal (k_s/k)$ is considered as a profinite topological group.