We have said that an algorithm is made up of a sequence of actions, so we should say a little more about what an action is. For our purposes, an action should:
From the criteria above, it should be apparent that an algorithm's recipient - that is, the person or thing that we expect to follow the algorithm - is of critical importance. For example, “raise your right hand” is a perfectly reasonable action for most adult humans. However, for a toddler who does not yet know right from left, it is not an appropriate action, because it is not self-explanatory. For a computer, it is not even a possible action, since computers do not typically have hands at all!