Language is one of the most precious gifts nature has bestowed upon us. It allows us to cooperate better with other individuals by enabling us to communicate useful and relevant information. What is it about language and our use of it that allows us to do so? It is the combination of stable linguistic rules and flexible reasoning. On the one hand, what we intend to communicate, - the meaning of the utterance - is to a large extent governed by shared rules that we all make use of. On the other hand, we often communicate more by the use of an expression than can be derived from these linguistic rules alone, and this depends on (features of) context and the assumption that speakers are rational cooperative language users. In this edited volume a number of leading scholars investigate which factors are favourable to the emergence and sustenance of linguistic rules, and how we use rationality principles to infer what is communicated in actual conversation. (Evolutionary) game theory provides the unified framework in which these issues are addressed and the Introduction to the volume provides the reader with enough background in game theory to follow the discussion.