Protein kinases are enzymes that use ATP to phosphorylate other proteins, which results in the alteration of their functions. These are signaling enzymes, which are responsible for regulating signal transduction in multiple intracellular processes such as glycogen synthesis, hormone responses, ion transport, proliferation, apoptosis, metabolism, transcription and antibiotic resistance. There are more than 30 families of kinases, of which protein kinase family is the largest. A few examples of protein kinases include AMP-activated protein kinase (AMPK), calcium calmodulin dependent kinases (CAMK), AGC kinase, casein kinase 1 (CK1), CMGC kinases, tyrosine kinases (TKs), and receptor interacting protein kinases (RIPKs). AMPK affects some major physiological functions such as metabolic activity. AMPKs are also critical for regulating lipid metabolism, mitochondrial function, and carbohydrate metabolism. This book includes some of the vital pieces of works being conducted across the world, on various topics related to protein kinases. It will also provide molecular insights on protein kinases to the readers. The book will serve as a valuable source of reference for graduate and postgraduate students.