Idiopathic pulmonary fibrosis (IPF) is the most common type of idiopathic interstitial pneumonia and has a dismal prognosis. Median age at IPF onset is 60-70 years and it is mainly related to cigarette smoke exposure. Its clinical profile is heterogeneous and different clinical phenotypes are now better defined: familial IPF, slow and rapid progressors, combined pulmonary fibrosis and emphysema, anti-neutrophil cytoplasmic antibodies/microscopic polyangiitis and IPF, and IPF associated with lung cancer. Acute exacerbation associated with rapid functional decline is an event that does not happen infrequently and affects survival. Diagnosis requires a typical usual interstitial pneumonia (UIP) pattern on computed tomography in the appropriate clinical setting or morphological confirmation of the UIP pattern when imaging findings are not characteristic enough. Surgical lung biopsy is the gold standard to obtain valuable information for histological analysis. However, less invasive procedures (transbronchial lung biopsy or even improved transbronchial lung biopsy by cryoprobes) are now under consideration. Prognostic indicators are mainly derived by pulmonary function tests. Recently, staging systems have been proposed.