Gastritis is a condition that inflames the lining of the stomach, causing belly aches, indigestion, bloating, and nausea. If left untreated, it can lead to complications and increase the risk of stomach cancer. The causes of gastritis include H. pylori infection, bile reflux, and infections. Symptoms include nausea, vomiting, and indigestion. Treatment options include antibiotics, acid-blocking medications, and lifestyle changes. Preventive measures involve practicing good hygiene, avoiding certain foods, reducing caffeine intake, managing stress, limiting alcohol consumption, and not lying down immediately after a meal.