A derivation of the conserved quantities arising from symmetries of the Lagrangian density under continuous transformations is reviewed with an eye to brevity and clarity. The derivation is sufficiently general to include virtually all cases of interest in field theory. Also covered is a separate and very short derivation which is valid only in the special case, frequent in quantum field theory, of internal symmetries where the transformations are independent of space-time. Some sources of confusion and error in the published accounts of the problem are noted.