A large class of production processes at the LHC can be thought as initiated by b-quarks: single-top, (pseudo)-scalars at large tan-beta, gamma, W and Z in association with b-jets. Over the years, predictions in QCD have become available in 4- and 5-flavor schemes, leading often to quite different, and therefore puzzling, results. I discuss how one can think about these schemes in an easy way so that to understand and solve the apparent differences and to make accurate and reliable predictions for the LHC.
