Flow cytometry is a technique for measuring both scattered light and fluorescence from single cells at very rapid rates. Typically up to 5000 cells can be analysed per second. Using various fluorochromes this allows a cell population to be analysed for cells showing certain characteristics such as the presence of a particular enzyme, cellular constituent or other gene product. The information it can provide is invaluable in helping to diagnose certain cancers as well as aiding pure research into many aspects of cell biology such as the cell cycle and gene expression. This book describes the technology in a simple and direct way. The fundamental concepts upon which the technology is based are outlined and the book goes on to describe flow cytometers and what can be gained from using them in biology and medicine. The book gives a particularly detailed account of how artifactual results can arise and where 'noise' is generated. Anyone starting to use, or already using this technique, will need to read this book.