Bronchitis is an inflammation of the bronchial tubes, which carry air to and from the lungs. It often occurs after a cold or respiratory infection and can be caused by viruses, bacteria, or irritants like smoke and pollution. Symptoms typically include a persistent cough, mucus production, wheezing, and shortness of breath. There are two main types of bronchitis: acute and chronic. Acute bronchitis usually lasts for a few weeks and often resolves on its own, while chronic bronchitis is a long-term condition that requires ongoing management. Treatment may involve rest, fluids, and medications to relieve symptoms.