Pulmonary fibrosis is a disease in which tissue deep in lungs thickens and becomes stiff, or scarred, over time. The formation of scar tissue is called fibrosis. Consequently, lungs can’t move oxygen into bloodstream and brain and other organs don’t get the needed oxygen need. Sometimes cause of fibrosis can be found, but in most cases, it is not cause. This is called as idiopathic pulmonary fibrosis (IPF)