The Conditional Turn-Based Battle System (abbreviated as CTB), is a turn-based RPG battle system. While battle systems similar to CTB exist in other games, the term "Conditional Turn-Based" has only been used in reference to Final Fantasy X. The CTB system is similar to the Active Time Battle (ATB) system seen in other Square games, such as Final Fantasy VII. Party members and enemies will have their turn order decided based on specific stats; however, the action taken by each character will determine how soon they may take their next action. For example, in Final Fantasy X, using an item will result in another turn sooner than using a powerful Overdrive ability. In addition, magic effects such as Haste and Slow will affect a character's time between action.
In Final Fantasy X, the turn order is shown on the right-hand side of the screen during a battle. When an action, such as using an item or casting a spell, is highlighted in the menu, the change to the turn order is reflected. In addition, highlighting targets for speed-modifying spells allows the player to see how the affected character's time between actions will change. This, combined with the ability to see enemy health bars and weaknesses, allowed for an extra layer of strategy during encounters.