What parts of a language can change, and how do languages diverge to the point where their speakers can no longer understand each other? Have all of the world’s languages been classified as to their family relationships? Are the Native languages of the Americas related to languages of Siberia and Europe? Language change is gradual, but we become aware of changes through contact with people of other generations, by reading what was written in earlier times, and by listening to old recordings. We will look at how languages change and explain the regularities that govern this change.