On 7 August 2025 OpenAI introduced GPT-5. It described a unified system: a quicker model for most questions, a deeper thinking model for harder ones, and a router that picks. It said the system was available to all ChatGPT users, with more usage for Plus and a GPT-5 pro mode for Pro.
For a newcomer: you no longer had to know whether to pick “GPT” or “o”. The product tried to choose. That is a kindness of design, if it works. OpenAI’s own page is the source for what it claimed that day.
Intelligence Age Gulf wrote this note on 30 September 2026.
Source. OpenAI, Introducing GPT-5, 7 August 2025.