What condition is characterized by inflammation of the gums?

Gingivitis is characterized specifically by inflammation of the gums, often resulting from plaque buildup on teeth. This condition often presents with symptoms such as redness, swelling, and bleeding of the gums, particularly when brushing or flossing. Gingivitis is typically considered an early stage of periodontal disease and is generally reversible with good oral hygiene practices.

The other options relate to different dental or oral health conditions. For example, periodontitis is a more advanced stage of gum disease that not only involves inflammation of the gums but also affects the bone and supporting tissues of the teeth, leading to tooth mobility and potential tooth loss. Halitosis refers to bad breath, which can be a symptom of various dental issues but is not a condition characterized by inflammation. A fistula is an abnormal connection between two tissues or organs, which in dental contexts can occur as a result of infection and is not specifically related to gum inflammation. Therefore, gingivitis is the correct answer, focusing solely on the inflammation of the gums.