Hepatitis A is a highly contagious viral infection that affects the liver, caused by the Hepatitis A virus (HAV). It is primarily transmitted through ingestion of contaminated food or water, or close contact with an infected person. Symptoms can include fatigue, nausea, abdominal pain, jaundice, and fever, although some individuals may be asymptomatic. Vaccination is an effective way to prevent the infection, and good hygiene practices can help reduce transmission.