Number is the most underestimated of the grammatical categories. It is deceptively simple yet distinctions in number (as in cat versus cats ) vary considerably from language to language. Some languages, for instance, make more distinctions than English, having three, four or even five different values. This book draws on examples from many languages to analyze the possibilities and reveals that the world's linguistic resources are richer than even many linguists realize. It is intended for linguistic students and teachers and is an ideal entry to linguistic typology.