You say potayto and I say potahto

How Language Works covers much the same ground as many current introductions to linguistics but goes beyond these by discussing in greater detail many of the topics that attract public interest but are not always regarded as "serious" mainstream linguistics: body language, the (unknown) origins of language, attitudes towards dialects, the languages of advertising or the law and so on. As with all of David Crystal's prodigious output, the writing is crisp and clear and informative without being overly technical.

The main section headings indicate the topics Crystal covers: spoken language (both the production and the perception of speech); written language (including an illuminating overview of the development of writing systems); sign language; language structure (which follows a fairly traditional morphology-syntax-semantics levels of description approach); discourse; dialects; languages (an overview of some of the methods of comparative philology and a description of the main language families); multilingualism - reminding us forcefully that most of the world's inhabitants speak two or more languages; and a final section on looking after languages, in which the topics of language planning and the topical issues of language preservation and language death are covered.

Some of these topics are covered in greater detail than others. For example, the section on speech is a fairly complete introduction to the discipline of phonetics and would be adequate for an introductory undergraduate course on this topic. Others are not so comprehensive, and Crystal does not refer as often as he might to the current technical literature in linguistics. For example, the section on grammar is very good on ways in which grammar has been taught (or not) in schools over the past 100 years, and on the motivation for studying grammar, but gives only a rather sketchy overview of notions such as constituent structure. I think that this is a bit of a missed opportunity. Admittedly some current theories of syntax are recondite in the extreme and would be impossible to describe in a book such as this, but in a book titled How Language Works - and in the area of language where we probably have the most detailed theories about "how it works" - it is a pity not to have some of the more compelling and accessible examples in the literature mentioned (for example, Noam Chomsky's hypothesis for why in some dialects of English, people say things such as "I wish I was taller than what I am").

Similar comments apply to the sections on semantics and the pragmatic notions of implicature and relevance (concerned with the implicit chains of reasoning we construct to interpret a response such as "It's late" as probably meaning "No" in answer to an offer of another beer.) Another example from the area of discourse might be Herb Clark's fascinating claims that fillers such as "er" and "um", far from being the symptoms of hesitation or dysfluency they have usually been described as, are part of a sophisticated system by means of which speakers try to ensure optimal reception on the part of their listeners. Yes, some of this literature can get quite technical, but if anyone could present these findings to a wider audience it is Crystal.

He is not afraid to wade into some of the more emotive topics to do with language. He attacks some of the examples used in Eats, Shoots and Leaves -type literature for displaying "linguistic ignorance", pointing out that forms such as "potato's" were common in earlier forms of English and that we still use those such as "the 1920's" without adverse comment. There is, he says, "a logic behind such forms which the modern users are unconsciously manifesting". Crystal is quite scathing about those who, "believing in the inviolability of the small set of rules that they have managed themselves to acquire... condemn others from a different dialect background, or who have not had the same educational opportunities as themselves, for not following those same rules".

Crystal traces this attitude back to the prescriptive grammar movement of the 18th century. While this may be so, I suspect some of his targets are motivated more by the attitude described some years ago by Geoffrey Pullum: speakers of Received Pronunciation (or some other prestige dialect) regard possession of this way of speaking as a valuable investment - it may literally be that in some cases, of course. To find others disregarding or "disobeying" the rules of this dialect is to have your investment devalued, and nobody likes that.

Whereas How Language Works is really a textbook, encyclopedic and written in a formal though accessible style, Words, Words, Words is a shorter and much less dense book, written in a more journalistic and popular manner.

Plenty of sentences with no main verbs, for example. In this book, Crystal tries to answer any questions one might have about words: how many are there in present-day English, where do they come from, how do we define them, how are they built up, and so on.

Again, he covers many of the areas given short shrift in traditional linguistics books: sound symbolism, slang, the semantic content of proper names, the role of swearing, and popular lists of favourite words (the top few "beautiful" words in a recent poll were "mother", "passion", "smile", "love" and "eternity", from which the hard-nosed linguist is going to gain little other than an appreciation of the sentimentality of people who participate in such polls). The presentation is snappy, with many different fonts, nicely chosen photographs, and many of those inset panels beloved of schoolbooks imitating a torn-off page from a spiral-bound notebook - now what on earth is the word for those?

Inevitably there is occasional overlap between the books: the "potato's"

example is used again, as is a nice example of the difficulty of giving precise definitions: the little girl who called a kitchen a factory because she had been told that a factory is where things are made, and so, of course, is a kitchen.

Again, I would have welcomed some diluted mention here of the extensive philosophical and linguistic literature on words, concepts and definitions: the little girl has clearly never read Jerry Fodor's work, poor thing, or she would have realised that virtually no definitions outside of mathematics are bi-conditional, only conditional: if it is a factory, then it is a place where things are made, but not invariably vice versa. It is not clear whether Crystal thinks that bi-conditional definitions are impossible or just difficult to arrive at.

He has a lot of fun with made-up words. His own "debagonization" means "the cessation of anxiety when our luggage eventually emerges from the black hole of an airport carousel". My favourite was the redefinition of the proper name "Beccles", attributed to Douglas Adams: "The small bone buttons placed in bacon sandwiches by unemployed guerrilla dentists". I think I will call those inset panels "spiralets", if they do not already have a name.

This is a hugely enjoyable book. Crystal's genuine enthusiasm for both the everyday phenomena of language and its curiosities and his evident urge to communicate that enthusiasm come through on every page.

Stephen Pulman is professor of computational linguistics, Oxford University.