The 20th century saw the transformation of the practices of tracheotomy, endoscopy and non-surgical tracheal intubation from rarely employed procedures to essential components of the practices of anesthesia, critical care medicine, emergency medicine, gastroenterology, pulmonology and surgery. The "digital revolution" of the 21st century has brought newer technology to the art and science of tracheal intubation. Several manufacturers have developed video laryngoscopes that use digital technology such as the CMOS active pixel sensor (CMOS APS) to generate a view of the glottis so that the trachea may be intubated.