Charisma measures a character's force of personality, persuasiveness, ability to lead, and physical attractiveness. It represents actual personal strength, not merely how one is perceived by others in a social setting. Charisma is most important for paladins, sorcerers, and bards. It is also important for clerics, as it affects their ability to turn undead. All characters benefit from having a high charisma when speaking with others in the world. Charisma affects an NPC's initial reaction to the player and it modifies the player's persuasion skill checks.
Note: Charisma influences bard/sorcerer spells, not intelligence.
The base charisma score is used to determine the highest level spell a bard or sorcerer can learn. This maximum spell level is the score minus ten.
The charisma modifier is added to the DC of spells cast by a bard or sorcerer. In addition, bards and sorcerers gain bonus spell slots based on this modifier; for details see ability modifier. Furthermore, the charisma modifier is added to the animal empathy, bluff, intimidate, perform, persuade, taunt, and use magic device skills.
Prestige classes that use the charisma modifier for some of their class features include blackguards and champions of Torm.