Human embryonic stem cells (hESCs) have been recognized as the "gold standard" for research on pluripotency and differentiation, and hold great promise for advancing our knowledge of human development, biology, disease and therapy. However, traditional techniques for generating hESCs rely on surplus IVF embryos and are incompatible with the generation of genetically diverse, patient- or disease-specific stem cells. A recent breakthrough in stem cell biology is the success of converting human somatic cells into pluripotent cells by using defined "reprogramming factors". While these reprogrammed cells have similar developmental potential as authentic hESCs, they are not derived from human embryos, and are thus termed "induced pluripotent stem cells (iPSCs)". The iPSC technology would prove useful for generation of individual cell lines from many different patients to study the nature and complexity of disease. Moreover, problems of immune rejection for future therapeutic applications would be greatly relieved by being able to generate reprogrammed cells from individual patients. Although iPSC generation is still slow, inefficient, fraught with pitfalls, and unsafe for human use, recent research has yielded exciting insights into the understanding of the technology, logic, safety, and utility of iPSCs, and has led to the use of these unusual cells for disease modeling, drug discovery and regenerative medicine, paving paths to new therapeutics.