The bronchus (or pleural, the bronchi), are the airways that lead from the trachea into the lungs, and then branch into smaller bronchioles.
The bronchi are conducting passages for air into the lungs. A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi to branch from the trachea at the carina are the right main bronchus and the left main bronchus.
Your right and left main bronchi are the widest portions of your bronchi. Then your bronchi divide into branches that get smaller and smaller starting with: The lobar bronchi, which pass into a section (lobe) of your lungs.