Intelligence determines how well your character learns and reasons. This ability is important for wizards because it affects their Spellcasting ability in many ways. Creatures of animal-level instinct have Intelligence scores of 1 or 2. Any Creature capable of understanding speech has a score of at least 3. A character with an Intelligence score of 0 is comatose. Some creatures do not possess an Intelligence score. Their modifier is +0 for any Intelligence-based skills or checks.

You apply your character's Intelligence modifier to:

• The number of bonus languages your character knows at the start of the game. These are in addition to any starting racial languages and Common. If you have a Penalty, you can still read and speak your racial languages unless your Intelligence is lower than 3.
• The number of skill points gained each level, though your character always gets at least 1 skill point per level.
• Appraise, Craft, Knowledge, Linguistics, and Spellcraft checks.

A Wizard gains bonus spells based on his Intelligence score. The minimum Intelligence score needed to cast a Wizard spell is 10 + the spell's level.