Book excerpt: This new third edition updates a best-selling encyclopedia. It includes about 56% more words than the 1,392-page second edition of 2003. The number of illustrations increased to almost 2,000 and their quality has improved by design and four colors. It includes approximately 1,800 current databases and web servers. This encyclopedia covers the basics and the latest in genomics, proteomics, genetic engineering, small RNAs, transcription factories, chromosome territories, stem cells, genetic networks, epigenetics, prions, hereditary diseases, and patents. Similar integrated information is not available in textbooks or on the Internet.