Missions are essentially [ levels] that allow progress through the storyline of Saints Row. Strongholds, or "Stronghold Missions", are non-storyline missions which unlock additional neighborhoods. Strongholds silently become available after some missions, must be completed in order to unlock the final mission of each arc, and have a separate map filter. Respect is a form of currency that is used to start missions, and can be accumulated by playing Activities; which also unlock cash and other bonuses upon completion. Overall, there are 36 missions in Saints Row.