The management of the mechanical ventilator is one of the most complex and dynamic, yet ubiquitous issues to face the critical care physician. As we as a medical community have become more advanced, so too, have our ventilators, with new modes and variables having been added beyond more traditional modeslike Assist Control and Intermittent Mandatory Ventilation. This article is designed to give a very basic understanding of what the individual ventilatory modes do and how they are set.It is in no way meant to be a replacement for either a medical intensivist or a respiratory therapist.