  The main goal of this article is to expand the theory of invariants of
Artin-Schreier curves by giving a complete classification in genus 3 and 4. To
achieve this goal, we first establish standard forms of Artin-Schreier curves
and determine all isomorphisms between curves in this form. We then compute
reconstructing systems of invariants for curves in each connected component of
the strata of the moduli spaces for Artin-Schreier curves of genus 3 and 4 for
$p>2$.
