This book celebrates the 40th anniversary of the bar code and is written for those who over the years have asked the author what these bar codes are all about. It deals with why they were invented, who created them, how they are managed and used, whether they have been 'a good thing', how much longer they will last and what may replace them. It tells you how you can 'read between the lines' and 'what's in a number'. But it is not a detailed technical or historical account. It is an entertaining account full of stories and personalities designed to show that the term 'interesting bar codes' is not an oxymoron.