Wet rales are sounds produced by the rupture of blisters formed by gas passing through secretions such as exudate, sputum, blood, mucus and pus in the respiratory tract during inspiration, so they are also called blister sounds. Or it is thought to be the bursting sound produced by the wall of the small bronchus trapped and closed due to adhesion of secretions, which suddenly opens and re-inflates when inspiration is applied. Wet rales are one of the most important signs on auscultation of the lungs. Wet rales are one of the most important signs on auscultation of the lungs. It is often seen in bronchitis, pneumonia, bronchiectasis, pulmonary stasis, pulmonary edema, pulmonary infarction, etc. Then, the following is the differentiation classification of wet rales: Classification: 1, coarse wet rales: occurring in the trachea, main bronchus or cavity area, mostly in the early inspiratory period. 2, medium wet rales: occurring in the medium bronchial, more often appear in the middle of inspiration. 3.Fine wet rales: occurring in small bronchi, mostly appearing in the late inspiration. 4.Twisting sound: very fine and uniform wet rales, mostly heard at the end of inspiration. The mechanism of formation is due to gas passing through the respiratory tract, if there are secretions (such as sputum, exudate, blood, mucus, pus, etc.) in the respiratory tract, blisters will be formed, which are produced after the blisters rupture. It is divided into coarse, medium and fine wet rales and twisted sounds. The distribution may be limited or both lung fields may be full of wet rales.