Simulation models are only as good as the thinking behind them. The Ten Commandments of Process Simulation serve as a guideline to ensure engineers stay grounded in the fundamentals, focusing on clarity, purpose, and physical relevance. These principles emphasize starting with clear objectives, understanding the system, considering physical behavior, and maintaining discipline in basic practices like material balances, phase envelopes, and proper unit management. They are a reminder that the strength of a model lies not in its complexity but in how well it represents the real-world process it aims to simulate.