OpenAI o-series – reasoning models lineage explained
OpenAI's o-series is the company's line of reasoning models: systems built to spend compute thinking through a problem before they answer, rather than producing the most fluent…
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The frontier of embodied AI
Foundation models. Voice and speech AI. Avatars and synthetic video. Agentic infrastructure. Edge runtimes. And the trust-and-safety surface around them all – analysed by hand, written to last.
Foundation Models
OpenAI o-series – reasoning models lineage explained
OpenAI's o-series is the company's line of reasoning models: systems built to spend compute thinking through a problem before they answer, rather than producing the most fluent next token as fast as possible. The line began with o1-preview in September 2024, moved through…
Continue readingWhat we cover
Seven areas of embodied AI. Each is an ongoing body of work, continuously updated as the field moves.
- Foundation Models Frontier model families and the labs behind them.
- Voice & Speech AI TTS, voice cloning, STT, conversational and call-center AI.
- Avatars & Vision Synthetic video, talking avatars, 3D characters, motion capture.
- Agentic AI Agent frameworks, autonomous coders, RAG and agent infrastructure.
- On-Device & Edge AI Local LLM stack, edge hardware, small open models, on-device privacy.
- Trust & Safety Provenance, deepfake detection, AI governance, safety research.
- Industry Tracker Living trackers – open-source AI weekly, funding monthly.
The model lineage
Eight years of foundation models, in three families. Hover any release to read what it changed.
GPT
GPT-1 Jun 2018 117M params The first decoder-only GPT, trained on BookCorpus. The thesis: pre-train broadly, fine-tune cheaply. Read the analysis → GPT-1 Jun 2018 GPT-2 Feb 2019 1.5B params Coherent long-form generation. Released in stages over misuse concerns. Read the analysis → GPT-2 Feb 2019 GPT-3 May 2020 175B params Few-shot learning from prompt examples. The "scale is enough" bet, vindicated. Read the analysis → GPT-3 May 2020 GPT-3.5 Nov 2022 first RLHF The first RLHF model in the line, and the engine behind the original ChatGPT. Read the analysis → GPT-3.5 Nov 2022 GPT-4 Mar 2023 multimodal Vision input added. OpenAI stops disclosing architecture from here on. Read the analysis → GPT-4 Mar 2023 GPT-4o May 2024 omni Native audio, vision and text through a single shared forward pass. Read the analysis → GPT-4o May 2024 GPT-5 Aug 2025 400K context A unified system that routes between fast inference and deep reasoning. Read the analysis → GPT-5 Aug 2025 GPT-5.5 Apr 2026 MMLU 92.4% Codename Spud. The current flagship as of mid-2026. Read the analysis → GPT-5.5 Apr 2026
Llama
Llama 1 Feb 2023 research-only Leaked publicly within a week, which kick-started the open-weight era. Read the analysis → Llama 1 Feb 2023 Llama 2 Jul 2023 permissive The first genuinely commercial open licence. An accident turned into strategy. Read the analysis → Llama 2 Jul 2023 Llama 3 Apr 2024 8B / 70B Redefined what open models could do at their parameter scale. Read the analysis → Llama 3 Apr 2024 Llama 3.1 Jul 2024 405B · 128K The first open model to genuinely rival the closed frontier on benchmarks. Read the analysis → Llama 3.1 Jul 2024 Llama 4 Apr 2025 MoE · multimodal Scout and Maverick: mixture-of-experts, natively multimodal, 10M-token context. Read the analysis → Llama 4 Apr 2025
Stable Diffusion
SD 1.5 2022 512px The foundational open image model, with a vast derivative ecosystem still alive today. Read the analysis → SD 1.5 2022 SD 2.0 late 2022 OpenCLIP The underrated stumble. Changing the text encoder broke the community contract. Read the analysis → SD 2.0 late 2022 SDXL Jul 2023 1024px The recovery. Larger UNet, base-plus-refiner pipeline, dual text encoders. Read the analysis → SDXL Jul 2023 SD 3 Jun 2024 MMDiT A new transformer backbone, but a rocky initial release on human anatomy. Read the analysis → SD 3 Jun 2024 SD 3.5 Oct 2024 8.1B The return to form, and the current generation as of 2026. Read the analysis → SD 3.5 Oct 2024
Recent essays
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How to use ChatGPT – effective prompting
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Mistral AI – the European open model lab
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Living trackers
Two pieces we republish on a fixed cadence – analyst synthesis, not aggregation.