gpt-naming-o-prefix-reasoning-4o-omni

IN premise — summaries/2026/08/24/wiki-Large_language_model-chunk-6.md

Created 2026-08-24T17:11:17+00:00

In OpenAI's model naming convention, the 'o' prefix (o1, o3, o4-mini) denotes reasoning models using extended chain-of-thought, while '4o' (GPT-4o) denotes natively multimodal ('omni') capability

Summary

OpenAI uses the letter "o" two different ways in model names that are easy to confuse: as a prefix it signals a model built for extended step-by-step reasoning, while at the end of a name like GPT-4o it stands for "omni," meaning the model natively handles multiple input types such as text, audio, and images. Keeping these two conventions straight matters because the name alone is often the first clue to what a model is actually designed to do, and mixing them up leads to wrong assumptions about its capabilities.