No definition seems to adequately define language or be agreeable to everyone. There have been a number of attempts to determine the properties of human language, and different lists of features can be found. We will take six of these features and describe how they are manifested in human language. We will also try to describe in what ways these features are uniquely parts of human language and unlikely to be found in the communication system of other creatures. We can now consider some of the properties which are believed to be unique to the linguistic system of human beings.