This book summarizes mountains of research by various scientists in the field of general biochemistry, with an emphasis on enzymes which make all the important molecules in our body, such as DNA, proteins, etc. Enzymes are also essential for removing all toxic chemicals that inadvertently enter our body. All metabolic reactions in our body are performed by enzymes. But perhaps, most importantly, it should give the reader a satisfying feeling of knowing: "Aha! That is how my cells work.".