What is…
Open weights
A model whose trained parameters are published so anyone can download and run it themselves.
With a closed model (like the flagship ChatGPT or Claude models) you can only use it through the company's app or API. Open-weights models — such as Meta's Llama, Mistral's models, Qwen, DeepSeek and Google's Gemma — publish the weights, so you can run them on your own hardware, fine-tune them, and keep data fully private.
"Open weights" isn't always "open source": the training data and code are often not released, and licenses vary.
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Which of these describes Open weights?
Related terms
Parameters
The billions of internal numbers a model learns during training — its 'knowledge', stored as weights.
Fine-tuning
Extra training on a smaller, focused dataset to specialize a model's style, format or skill.
Quantization
Shrinking a model by storing its numbers with less precision, so it runs faster on smaller hardware.
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