This document summarizes Warren Buffett's four simple rules for making investment decisions: Rule 1 is to invest in clean and simple businesses like soft drinks, sweets, or food companies. Rule 2 is to invest in companies with favorable long-term prospects. Rule 3 is to invest in companies with an international franchise network and guaranteed growth prospects. Rule 4 is to invest in companies with strong leadership teams. The document provides examples for each rule and concludes by emphasizing that even great investors like Buffett failed at times but learned from mistakes.