In molecular biology, peroxisome proliferator-activated receptors (PPARs) are a group of nuclear receptor proteins. They function as transcription factors. PPARs control the rate of transcription of genetic data from the DNA to the messenger RNA. They play essential roles in the regulation of cellular differentiation, development, and metabolism of higher organisms. They are also involved in the transcriptional regulation of key metabolic pathways such as lipid metabolism, adipogenesis, and insulin sensitivity. There are three known types of PPARs, namely alpha, beta/delta and gamma. These are transcribed from different genes. This book explores all the important aspects of peroxisome proliferator activated receptors. Different approaches, evaluations, methodologies and advanced studies on this subject have been included herein. In this book, using case studies and examples, constant effort has been made to make the understanding of the difficult concepts of peroxisome proliferator-activated receptors as easy and informative as possible, for the readers.