What condition involves inflammation or infection of the gallbladder?

Cholecystitis is indeed the condition that involves inflammation or infection of the gallbladder. This typically occurs when a gallstone blocks the cystic duct, leading to bile accumulation and irritation of the gallbladder wall. This condition often presents with symptoms such as severe abdominal pain, nausea, vomiting, and fever. The inflammation can be acute or chronic, with acute cholecystitis requiring prompt medical attention and often surgical intervention to remove the gallbladder.

In contrast to cholecystitis, appendicitis refers to inflammation of the appendix, cholelithiasis refers to the presence of gallstones without necessarily causing inflammation, and gastritis is the inflammation of the stomach lining. Each of these conditions involves different anatomical structures and symptoms, further emphasizing the specificity of cholecystitis to the gallbladder.