This paper is based on Chapter Three of the book ‘Targeting customers — How to use geodemographic and lifestyle data in your business’ by Peter Sleight. It provides a straightforward introduction to using geodemographic information systems. It reviews the rationale for neighbourhood classifications, how they are constructed, the arrival of the new census data and the implications for new products. Finally, it reviews the neighbourhood issues implicit in the assumption of such classifications. The third edition of ‘Targeting customers’ is published to coincide with the new system launches following the release of the 2001 Census data. The book (published by World Advertising Research Center, www.warc.com) was published in March 2004.