Some Languages Have No Grammar

It is not uncommon to hear people say of a language that it doesn't have any grammar. But if a language has no grammar then it would be impossible to make a mistake. There would not be a difference between nouns and verbs or other word classes. You would only be able to communicate with very simple messages. It could not have little words. It would not be possible to mark the differences between the sentences by changing the 'tune' or intonation of the sentence. There would be no rule about word order. All languages have rules and therefore they all have grammar.