This is an introduction to the history of languages, from the distant past to a glimpse at what languages may be like in the distant future. It looks at how languages arise, change, and ultimately vanish, and what lies behind their different destinies. What happens to languages, he argues, has to do with what happens to the people who use them, and what happens to people, individually and collectively, is affected by the languages they speak.

The book opens by examining what languages the hunter-gatherers might have spoken and the changes to language that took place when agriculture made settled communities possible. It then looks at the effects of the invention of writing, the formation of empires, the spread of religions, and the recent dominance of world powers, and shows how these relate to great changes in the use of languages. Tore Janson discusses the appearance of new languages, the reasons why some languages spread and others die, considers whether similar cyclical processes are found at different times and places, and examines the causes of internal changes in languages and dialects.

The book ranges widely among the world's languages and mixes thematic chapters on general processes of change with accounts of specific languages, including Chinese, Arabic, Latin, Greek, and English.