This document discusses oral cancer, including its definition, types, signs and symptoms, epidemiology, etiology, risk factors, and prevention. Oral cancer is defined as an indurated, ulcerated lump or sore in the mouth that may be painful and associated with cervical lymph node swelling. Tobacco use, including chewing tobacco, is the main risk factor and causes around 90% of oral cancers. Prevention strategies include education programs, screening and early detection, and maintaining good oral hygiene.