Final answer:
Crackles, is also known as crepitation, are abnormal lung sounds that can be heard during breathing. They are caused by the movement of air through narrowed or fluid-filled airways. Crackles can be a sign of respiratory conditions like pneumonia, bronchitis, or COPD.
Step-by-step explanation:
Crackles, also known as crepitation, are abnormal lung sounds that can be heard during breathing. They are caused by the movement of air through airways that are narrowed, filled with fluid, or have a disrupted lining. Crackles can be a sign of various respiratory conditions, such as pneumonia, bronchitis, or chronic obstructive pulmonary disease (COPD).