Intelligence measures mental swiftness and acuity, accuracy of recall, past education and learning, and the ability to reason.
Characters with high Intelligence scores are more likely to be able to read strange arcane writings, remember obscure passages of historical and religious texts, and understand the workings of the natural world.
Your Intelligence score applies in the following situations:
Intelligence is frequently used to recall details of the shared adventure world, representing memory and education—knowledge obvious to a character even if unknown or forgotten by their player. It is also used when you need to draw on logic or deductive reasoning.
Some examples of Intelligence Tests include:
The Artificer and The Wizard classes (as well as subclasses that draw from the Wizard spell list, like the Arcane Trickster and the Eldritch Knight) use Intelligence as their Spellcasting Ability Modifier, which determines their Spell Attack Bonus (how easy it is to hit other people with spells) and Spell Save DC (how hard it is for creatures targeted by their spells to resist their effects).