“What’s in a name? as Shakespeare said, calling a mode of mechanical ventilation by different names, will not change the mechanism by which the ventilation aids an ailing patient. However, an understanding of the nomenclature of modes of mechanical ventilation will help the practicing physicians when it comes to the selection of an appropriate mode. The wide array of modes of mechanical ventilation are based on the foundations of three basic variables, namely flow, volume, and pressure. The final section of this chapter describes these foundational modes of volume control, pressure control, and pressure support modes with their variations and their implications for clinical practice. For the description of flow-control ventilation (FCV), please refer to chapters “ The Respiratory Physics and Mechanics of Flow-Controlled Ventilation ” and “ Flow-Controlled Manual Ventilator (FCmV): A New Horizon in Elective and Emergency Airway Scenarios ”.