This book explores the importance of Single Nucleotide Polymorphisms (SNPs) in biomedical research. As SNP technologies have evolved from labor intensive, expensive, time-consuming processes to relatively inexpensive methods, SNP discovery has exploded. In terms of human biology, this research, particularly since the completion of the Human Genome Project, has provided a detailed understanding of evolutionary forces that have generated SNPs. It also has shown how SNPs shape human variation. The ability to inexpensively generate and analyze vast amounts of genetic data is poised to transform our understanding of human evolution and biology.