The copious production of charm quarks at HERA yielded measurements of the charm contribution to the proton structure and of the charm mass and fragmentation parameters of charmed hadrons. Several measurements of charm production in deep inelastic scattering from the H1 and ZEUS Collaborations as well as combined data are presented. A QCD fit to the charm data leads to a measurement of the charm quark mass and provides precise predictions e.g. for W and Z production at the LHC. D* photoproduction cross sections have been measured at 3 different ep center-of-mass energies, √s.  The √s dependence of the data is compared to next-to-leading order QCD predictions.  Charm fragmentation fractions in photoproduction to ground state charm hadrons are compared to e+e- data and support the hypothesis of fragmentation independence of the production process.