It seems quite clearly unjust to pay two people different amounts of money for doing the same work. But it is not as easy as it appeals at first sight to introduce equal pay for equal work.Two people may be working side by side in a factory and doing the same work, but one may be doing it twice as fast as the other; or one may be making no mistakes, while the other is making a lot. In some kinds of work, one can solve the problem of speed if one pays by the amount of work to be done and not by the hour: work paid for in this way is called piece-work. But it is not always possible to do this, so it is sometimes useful to pay workers at different rates, which take differences in skill into account. This usually means that the younger and therefore less experienced worker gets less than the older and more experienced one, which seems reasonable enough.