What is Base Attack Bonus?!?!?!?

[SylensetheBard]

I've always been a sorceress or rogue, and now want to be a fighter, but many of the special feats attached to that require a certain Base Attack Bonus and I know what that is but have no idea where it comes from or where I get any!!! I feel like an idiot...help me???

[Xandax]

Base Attack Bonus is the "attack" your character would have before any bonuses and/or modifiers are calcualted in, such as attack modifiers from strenght, weapon enchantment and so on.
Thus it is the attack bonus gained only based on your level and classes.

Depending on game version there is a table which shows the progression in both the orignal NwN games manual and in the HotU manual.
Your current BAB can also be seen on the character screen.