On September 12, 2024, OpenAI introduced its o1 model in a post titled “Learning to reason with LLMs.” The page presents o1 as a model trained to spend more time thinking through a problem before responding, producing an internal chain of reasoning rather than answering immediately.
This approach marked a shift in how language models are designed to work. Instead of relying solely on patterns learned during training to produce an instant answer, o1 was built to reason through difficult problems in steps, which improved its performance on tasks in areas such as mathematics, science, and coding.
o1 was the first widely deployed reasoning model and established a new product category. For businesses, it signaled that AI systems could be directed at harder analytical and technical problems where careful, multi-step reasoning matters more than speed, and it set the template for the reasoning-focused models that followed across the industry.