Missions are optional quests that can be undertaken in Crisis Core -Final Fantasy VII-. New missions become available as the player progresses in the game. They can be accessed by opening the menu whenever the player is at a Save Point at any point in the game.
There are several groups of Missions, as seen below. As the player progresses in the Missions, new ones from that Group become available. Missions give various exclusive Materia, Accessories, and Items that cannot be obtained in any other way. There are also special Digital Mind Wave types that can be unlocked. They are also the only way to return to past locations once Zack Fair has completed a section of the game. The most powerful enemies can be found in the latter Missions. Several characters, such as Yuffie Kisaragi make cameo appearances.
In all there are exactly 300 Missions, and can make the bulk of playtime if the player wishes to complete everything in the game.
List of all the Mission groups in Crisis Core: