As best I can tell, cultural theory aims to understand culture (or cultures) in an interdisciplinary way, drawing mainly on philosophy and the human sciences (especially sociology and anthropology), with perhaps a few ideas of its own thrown in to produce a fairly eclectic mix.
This book surveys cultural theory by describing more than 350 key concepts from the field, with the length of each entry typically being intermediate to a dictionary and encyclopedia. Examples of the concepts are absence, authority, civic humanism, counterculture, dramaturgical model, feudalism, ideological state apparatus, libertarianism, myth, philosophy of language, propoganda, ritual, sociobiology, syntagm, and youth culture.
As you can see, the concepts range from the familiar to the highly esoteric. Since the book has two editors and thirteen contributors, the quality of the entries likewise varies somewhat, and you will occasionally encounter some which are too unclear, although most are quite good and some are outstanding.
I read this book from cover to cover, and the net effect for me was that it was enlightening, often to the extent of being a page turner, which is saying a lot for a book organized alphabetically. The book would, of course, also be useful to look up concepts on an as-needed basis, as well as for randomly dipping into.
Highly recommended to people with an interest in relatively highbrow intellectual sort of stuff.