Pulmonary fibrosis, also commonly known as 'hardening of the lungs,' is a chronic and progressive lung disease. In this condition, the lung tissue, which is normally elastic and spongy, becomes damaged due to various causes and turns into scar tissue, causing the lungs to thicken and stiffen. This leads to a loss of elasticity in the air sacs (alveoli) within the lungs. Consequently, the transfer of oxygen from the air sacs to the surrounding blood vessels becomes difficult, resulting in shortness of breath (dyspnea) in patients.