Bronchitis is an inflammation of the air passages within the lungs that can be caused by viral or bacterial infections, irritants like dust, or cold weather. There are two main types - acute bronchitis typically lasts up to two weeks while chronic bronchitis can persist for months or years. Common symptoms include cough, wheezing, chest tightness, and shortness of breath as the inflammation affects the lungs. Preventive measures include getting vaccinated against influenza and practicing good hand hygiene.