ChatGPT 4o ChatGPT 4o is the most advanced multimodal model released by OpenAI as of 2024. The “o” stands for “Omni,” highlighting its ability to handle text, vision, and audio inputs within a single unified system. It builds upon the foundation of GPT-4, but with major improvements in performance, speed, and versatility that position it as a true leap forward in general-purpose artificial intelligence.