Crackles are abnormal lung sounds that can be heard during breathing, often resembling a series of short, popping noises. They occur when air moves through fluid or mucus in the airways, typically indicating conditions such as pneumonia, bronchitis, or heart failure. Crackles can be classified as fine or coarse, depending on their sound quality and the size of the airways involved. These sounds are usually detected using a stethoscope during a physical examination. Healthcare professionals assess crackles to help diagnose underlying respiratory issues. Treatment may involve medications, such as bronchodilators or diuretics, to address the root cause of the crackles and improve lung function.