In the last chapter, we focused on word meanings, saying nothing at all about word forms, that is, how words are produced and what they sound or look like. In this chapter, we'll focus on form, specifically the units that make up words and how those units are combined. We'll see that, just as meaning is organized around the way that people divide the continuous world into a set of categories, form is organized around the way that people divide the continuous space of possible sounds (or gestures for sign language) into a set of categories. We'll also meet dimensions and values again, this time dimensions relating to how the units of form are produced by the Speaker. We'll also see that while different languages have quite different sets of categories, different patterns for combining them into words, and even different dimensions, there are also obvious constraints on what is possible in word forms in human languages. This, and the next chapter, will be the only ones in the book dedicated almost exclusively to form. Linguistic form, however, is always in service of meaning, and we will see that the function of the basic form categories is to distinguish words, that is, patterns with different meanings, from one another.