Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease seen in patients with obesity, diabetes, and metabolic syndrome. Metabolic syndrome is an important predictor of the severe form of NAFLD, nonalcoholic steatohepatitis (NASH), and NASH patients with diabetes have an increased risk of liver cirrhosis and hepatocellular carcinoma. With the prevalence of obesity and diabetes around the world, NAFLD has become a global public health problem. NAFLD is not only one of the most important causes of liver-related disability and mortality, but also associated with the increasing incidence of diabetes and cardiovascular disease. The effective prevention and treatment of NAFLD is expected to reduce the burden of liver disease and cardiovascular disease. Therefore, this article overviews the advances in the diagnosis, prevention, and treatment of NAFLD.