This comprehensive volume is the most complete and up-to-date survey of gene quantification methods and technologies. Gene quantification is proving invaluable in biological research for comparing patterns of gene expression and in medical research for deciphering pathological processes. Such a potential to approach biological problems on a genome-wide scale may revolutionize the life sciences in the same way the amplification techniques have transformed the diagnostics of disease in the late 1980s. We are currently seeing an explosive growth and refinement in gene quantification methodology. These technological developments not only allow for faster and more robust quantification but also introduce new paradigms, e.g. a concept of accurate quantification using PCR without a standard. The major challenge addressed by most methods in this book is the quantification of nucleic acids from a minute amount of material. Hence the common theme to all gene quantification methods presented is the fact that quantification requires amplification, either controlled gene amplification or signal amplification. Special attention has been given to a distinction between relative quantification, usually sufficient for biological applications, and accurate quantification, instrumental for medical/clinical applications. Proper validation of standards, essential for accurate quantification, is also addressed.