The answer to the current main question of life, the universe, and everything.

o4‑mini

• “o4” is read as “O‑fourth” – a model focused on Reasoning (deep “chain‑of‑thought”) and visual analysis (e.g., sketches on a “whiteboard”).
• Released April 16, 2025; available to all ChatGPT users and in the API (there is a paid “o4‑mini‑high” for higher accuracy and speed).

GPT‑4o‑mini

• “4o” is read as “four‑Omni” – a smaller, cheaper multimodal version of GPT‑4o (text + images + audio).
• Appeared July 18, 2024, replacing GPT‑3.5 Turbo in free ChatGPT.

Mnemonic

• o4‑mini → O4‑very smart
• GPT‑4o‑mini → 4O can do whatever you want