Additional Study Information: This is a 5-year, longitudinal, observational study of patients with NAFL or NASH designed to specifically address important clinical questions that remain incompletely answered from registration trials. The main purpose of this research study is to collect and study information on patients with NAFLD/NASH.The goal of this study is to observe any treatment for NAFL/NASH in a large number of people in a real life setting. Researchers are interested in observing how these lifestyle changes, counseling, or other treatments work in patients who are treated by their doctors in routine practice. In the main part of the study, the past (up to 3 years before today) and future (up to 5 years from today) medical records (including any available liver pathology slides, imaging and labs) will be collected and sent to the sponsor to be stored in a private and secure computer database.Participants will also be asked to fill out a brief questionnaire about alcohol use. In addition to the main study, participants will be asked if they would like to participate in two optional sub-studies: Optional patient-reported outcome (PRO) survey substudy, and the Optional TARGET-NASH Biorepository Sub-Study. Participants will also be given the option to be contacted by the sponsor via e-mail or telephone if participants have stopped receiving care from the study doctor or to get updated information about their health if they are participating in the optional Biorepository Specimen Bank part of the study. Participation in this study may last up to 5 years.