Thinking, fast and slow is a way of understanding how our brains work. It helps us understand why we make certain decisions, and why we think the way we do. When thinking, fast and slow, we use both our intuitive mind (fast) and our more analytical mind (slow). Your intuitive mind (fast) is the part of your brain that makes quick decisions, reacting quickly to new information. Your analytical mind (slow) is where your brain works more slowly and carefully to think things through. Using both minds helps us make decisions more quickly and accurately.