Charge symmetry at the partonic level

s This review article discusses the experimental and theoretical status of partonic charge symmetry. It is shown how the partonic content of various structure functions gets redefined when the assumption of charge symmetry is relaxed. Various theoretical and phenomenological models for charge-symmetry violation in parton distribution functions are reviewed. After summarizing the current experimental upper limits on charge-symmetry violation in parton distributions, a series of new experiments are proposed, which might reveal partonic charge-symmetry violation or alternatively might lower the current upper limits on parton charge-symmetry violation.