At random intervals on the world map and in field mode, and at specific moments in the story, the game will enter the battle screen. This screen places the player characters on one side, the enemies on the other, and employs an "Active Time Battle" (ATB) system in which the characters exchange moves until one side is defeated. The damage (or healing) dealt by either side is quantified on screen. Characters have many statistics that determine their effectiveness in battle; for example, hit points determine how much damage they can take, and magic determines how much damage they can inflict with spells. Each character on the screen has a time gauge; when a character's gauge is full, the player can input a command for that character. The commands change as the game progresses, and are dependent on the characters in the player's party and their equipment. Commands may include attacking with a weapon, casting magic, using items, summoning monsters, and other actions that either damage the enemy or aid the player characters. "Final Fantasy VII" also features powerful, character-specific commands called Limit Breaks, which can be used only after a special gauge is charged by enemy attacks. After being attacked, characters may be afflicted by one or more abnormal "statuses", such as poison or paralysis. These statuses and their adverse effects can be removed by special items or abilities. When all the enemies are defeated, the battle ends and the player may be rewarded with money, items, and experience points. If the player is defeated, it is game over and the game must be restored to the last save point.