  After Jacobians of curves, Prym varieties are perhaps the next most studied
abelian varieties. They turn out to be quite useful in a number of contexts.
For technical reasons, there does not appear to be any systematic treatment of
Prym varieties in characteristic 2, and due to our recent interest in this
topic, the purpose of this paper is to fill in that gap. Our main result is a
classification of branched covers of curves in characteristic 2 that give rise
to Prym varieties. We are also interested in the case of Prym varieties in the
relative setting, and so we develop that theory here as well, including an
extension of Welters' Criterion.
