The syntactic principles of a language may insist on some order of words or may allow several options. For instance, English sentences normally must have words in the order Subject-Verb-Object. In Whales eat plankton, 'whales' is the subject, 'eat' is the verb, and 'plankton' is the object. Japanese sentences allow the words to occur in several possible orders, but the normal arrangement (when no special emphasis is intended) is Subject-Object-Verb. Irish sentences standardly have words in the order Verb-Subject-Object. Even when a language allows several orders of phrases in the sentence, the choice among them is systematically regulated. For example, there might be a requirement that the first phrase refer to the thing you're talking about, or that whatever the first phrase is, the second must be the main clause verb.