Final Fantasy XIII's Battle System DetailedS

Final Fantasy XIII is due out this year in Japan. For those who are unfamiliar with its battle system, let's learn about it. Everyday you should learn about something, you know.

Command Stock: Players selection which action they'd like to from a cluster of five "Action" slots.
Cost: Each of these five actions has a number attached to it and denote the number of slots a particular action requires.
Enhanced ATB (Active Time Battle): This refers to the bar under Lightning's name (the one with "444"). Players can perform various actions before it is empty. Commands with higher "Cost" drain the ATB bar faster.
Symbol Encounter: Enemies appear on the game's map. There is no battle screen transition.
Chain & Bonus: Found at the screen's top right. "Chain" refers to the number of consecutive hits inflicted. It's not clear what "Bonus" refers to, but Famitsu thinks it's related to Final Fantasy VII's Limit Break.
Enemy HP: The HP and names of your foes are displayed — unlike previous games.

More Details About Final Fantasy XIII Battle System, Vanille And The Demo [PS3 Hyper]