An important design feature of human language is the fact that larger units are composed of smaller units, and that the arrangement of these smaller units is significant. For example, a sentence is not just a long series of speech sounds; it is composed of words and phrases, which must be arranged in a certain way in order to achieve the speaker's goals. Similarly, words (in many languages) may be composed of smaller units, each of which has its own meaning, and which must be arranged in a particular way.

In order to analyze the structure of a word or sentence, we need to identify the smaller parts from which it is formed and the patterns that determine how these parts should be arranged. This chapter introduces some basic aspects of word structure (morphology), and some techniques for analyzing it. More complicated aspects of morphological structure will be discussed in chapters 13–17.

Section 2.1 deals with the problem of identifying the component parts of a word. The association between form and meaning, which we discussed in chapter 1, plays a critical role in this process. Some of the basic techniques we will need are also useful for analyzing sentences, and we will first introduce them in that context. Section 2.2 discusses the kinds of parts which can be combined to form words, sections 2.3–2.4 provide a method for displaying the arrangement of these parts, and Section 2.5 gives a brief overview of the different types of word structure found in the world's languages.