Hepatitis is a medical condition where the liver becomes inflamed and swollen. The liver is one of your body's most important organs: it filters toxins from your blood, helps digest food, and stores energy. When someone has hepatitis, their liver can't do these jobs as well.

The word comes from Greek: hepat- means liver, and -itis means inflammation. Doctors use this same -itis pattern for other inflammatory conditions, like appendicitis (inflamed appendix) or tonsillitis (inflamed tonsils).

Hepatitis usually happens when viruses infect the liver. Scientists have identified several types, named with letters: hepatitis A, B, C, and so on. Some types cause short illnesses that the body fights off, while others can become chronic, meaning they last a long time and need ongoing medical care. People with hepatitis might feel tired, lose their appetite, or notice their skin or eyes turning yellowish (a condition called jaundice).

Modern medicine has developed vaccines that prevent some types of hepatitis, and treatments that can cure or manage others. Thanks to these advances, doctors can now protect people from hepatitis or help them recover, keeping their livers healthy and functioning properly.