Pulmonary nodules are small, round growths in the lungs that can be detected through imaging tests like X-rays or CT scans. They are usually less than three centimeters in size and can be caused by various factors, including infections, inflammation, or benign tumors. Most nodules are not cancerous and often require monitoring over time. In some cases, pulmonary nodules may indicate the presence of lung cancer or other serious conditions. Doctors typically evaluate nodules based on their size, shape, and growth rate. Further tests, such as biopsies, may be needed to determine the nature of the nodule and guide treatment options.