Inference is a process of deriving new knowledge, given existing knowledge, and a number of rules. In logic, there are three different forms:

• Deduction. Given some facts, and some rules, derive new knowledge. The best known case of this are syllogisms: All men are mortal, Socrates is a man, therefore Socrates is mortal. This is usually called deduction.
• Induction. In a car, the brake is used; the car slows down; therefore: using the brake will slow down the car. This is called induction.
• Abduction. Using the brake in a car will slow down the car; the car slows down; probably, the brake was used. This is called abduction.