Invasive mechanical ventilation is a lifesaving intervention for patients with respiratory failure. The most commonly used modes of mechanical ventilation are assist-control, synchronized intermittent mandatory ventilation, and pressure support ventilation. When employed as a diagnostic tool, the ventilator provides data on the static compliance of the respiratory system and airway resistance. The clinical scenario and the data obtained from the ventilator allow the clinician to provide effective and safe invasive mechanical ventilation through manipulation of the ventilator settings. While life-sustaining in many circumstances, mechanical ventilation may also be toxic and should be withdrawn when clinically appropriate.