Non-alcoholic fatty liver disease (NAFLD) refers to a type of liver condition characterized by fat accumulation in the liver that affects people who drink little to no alcohol. It is classified into two types, namely non-alcoholic steatohepatitis (NASH) and non-alcoholic fatty liver (NAFL). NASH is a progressive variant of NAFLD that causes fibrosis and liver damage. NAFLD and NASH can be diagnosed using imaging tests, liver biopsy, and blood tests. Liver biopsy is used to reliably distinguish between NAFLD and NASH. The first line of treatment for NAFLD and NASH is weight loss, which can be achieved through a combination of healthy diet, calorie reduction, and exercise. Losing weight can also help decrease the inflammation and reduce the build-up of fat in the liver. Some of the diverse topics covered in this book address the causes, diagnosis, and therapies for NAFLD and NASH. A number of latest researches have been included to keep the readers up-to-date with the global concepts in these medical conditions.