The latest iteration in the GPT-5 series, known as GPT-5.1, aims to significantly enhance the intelligence and conversational abilities of ChatGPT. This update features two separate model types: GPT-5.1 Instant, recognized as the most popular option, is characterized by a warmer demeanor, improved instruction adherence, and heightened intelligence; on the other hand, GPT-5.1 Thinking has been fine-tuned as an advanced reasoning engine, making it easier to grasp, quicker for simpler tasks, and more diligent when tackling complex issues. Additionally, queries from users are now intelligently directed to the model variant that is best equipped for the specific task at hand. This update not only focuses on boosting raw cognitive capabilities but also on refining the communication style, resulting in models that are more enjoyable to interact with and better aligned with users' intentions. Notably, the system card addendum indicates that GPT-5.1 Instant employs a feature called "adaptive reasoning," allowing it to determine when deeper thought is necessary before formulating a response, while GPT-5.1 Thinking adjusts its reasoning time precisely in relation to the complexity of the question posed. Ultimately, these advancements mark a significant step forward in making AI interactions more intuitive and user-friendly.