Glossary

Open weights

'Open weights' means a model's trained parameters are downloadable and runnable (e.g. Gemma 4, Qwen, Mistral). That is distinct from 'open source' (weights plus a permissive license like Apache 2.0) and 'fully open' (weights plus training data and code, e.g. OLMo 3). Open weights can still carry usage restrictions. Llama 4's license, for instance, forbids EU use.

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