One point all linguists probably agree on is the centrality of words to language. All aspects of language are tied in some way or other to words. In this chapter, we'll start off imagining a world with no language at all and see what is gained by adding just this one basic feature of human language. Words have two aspects, their forms and their meanings, and in this chapter we'll only look at meaning. Actually we'll only be considering words in one category, those words that refer to things in the world. How people use words to refer is just one aspect of the question of what it means to mean, which turns out to be an enormously complicated topic, one where linguists and other cognitive scientists still have a long way to go. In a way the book is starting off with the hardest topic of all. But the idea of meaning is at the heart of what language is, so we can't really put it off. Even just scratching the surface of this topic, as I'll do in this chapter, will lead us to look at notions that seem to be beyond language: how people categorize objects in the world and how people use one kind of situation to help them understand another kind of situation. But to say anything at all about the meanings of words seems to require an account of where those meanings come from and what good they are for us.