Base Attack Bonus

The Base Attack Bonus (or BAB) is a number that represents a character or monster's skill at fighting that comes purely from his or her profession, training, and personal experience.

Benefits
Base Attack Bonus serves several roles in DDO:
 * It is added to all attack rolls with any weapon, including bare hands.
 * It determines the number of attacks in your attack sequence.
 * It determines player attack speed:
 * For melee weapons, attack speed increases at BAB 1, 3, 5, 10, 15, 20, and 25
 * For bows and thrown, attack speed increases with each point of BAB, and it grows much faster than for melee.
 * Several combat-related feats require a minimum BAB to unlock.

Progression
The BAB progression for players is based on their class (for creatures, on their HD), and follows one of the three following progressions:
 * +1 BAB per level, the best BAB progression, is reserved for the warrior classes (Barbarian, Fighter, Paladin, and Ranger).
 * +.75 BAB per level, the second best BAB progression, is used by the Artificer, Bard, Cleric, Druid, Favored Soul, Monk, and Rogue.
 * +.5 BAB per level, the worst BAB progression, is used by the Sorcerer and the Wizard. Epic levels also use this progression.

Since fractions are dropped rather than rounded, only classes in the first category start with a BAB of +1. Base Attack Bonuses gained from different classes, such as when a character is a multiclass character, add together. For example, if for some strange reason you are a character level 3 with 1 level of rogue, 1 level of bard and 1 level of sorcerer, your base attack will still be 0.