Active Time Battles

I've never really understood them.  Crono Trigger was the farthest I got in understanding one, but mostly because I spammed on physical attacks for pretty much everything.

I borrowed FF7 from a friend of mine a long time after it came out because I never owned a PS1, and I could not really figure out what I was really supposed to be doing.

Do you really just wait for the bars to fill up so you can do something while hoping that the enemy's doesn't fill up first?

Can someone help a rpg-noob who missed out on the SNES, PS1, and everything from Sega generations understand how you're actually supposed to play ATB systems?

Well, with the ATB system you have to wait until the bars fill up, then you can perform a action.
I think that it's the best battle system in the FF series since it also adds  time based strategy

Yeah, instead of waiting for your turns to come, you wait for your bar to fill. It doesn't really mean much is different than if you actually had turns, it just means that you have to rush a little so your enemies don't kill you while you're choosing your move.

Hmm...I guess I understood that part from what I played.  Maybe I just don't like it.

Best ATB system in my opinion, Baten Kaitos Origins.

It's where you have to wait X seconds to perform an action rather than wait until the other guy's turn is over

I'd like to add that most ATB systems are also dependent on your characters' speed/agility attribute.  The more you improve it, the faster your character will act.   Abilities such as haste, slow and stop also affect the ATB.  If you've played Chrono Trigger or FFX-2, the ATB is fundamental in doing more damage by way of double and triple techs or by chaining attacks when the ATB is full for your party. 

So if you just ended up 'spamming' single attacks one after another in Chrono Trigger you pretty much missed out on some awesome beat downs.

I hate ATB. I prefer everyone to wait their god damn turn.

You want to burn me with your spell? Wait your turn bitch! I still have to stab you dead.