GPT-o1, rolled out in September 2024, introduced chain-of-thought reasoning. This new model design thinks before it answers. Instead of guessing, it breaks problems into steps, double-checks its work, and delivers more accurate results, even if it takes longer. Aimed at developers, it’s smarter than most humans, with a 120 IQ, making it ideal for building better AI systems and apps. This makes it more like our own Human brains, interestingly.