What Is Open-Weight Model?
Open-Weight Model is an AI model whose trained parameters (weights) are publicly released, allowing anyone to run, fine-tune, or build on it.
Open-Weight Model — an AI model whose trained parameters (weights) are publicly released, allowing anyone to run, fine-tune, or build on it.
Open-weight models are sometimes loosely called "open source", but the terms differ: releasing weights is not the same as releasing the training data and code needed to reproduce the model. Open weights bring governance trade-offs — they enable scrutiny, customisation, and reduced vendor lock-in, but also make it harder to enforce safety guardrails or restrict misuse once the weights are distributed. This tension is central to current policy debates about how to regulate the most capable models.
Source: NIST AI 100-1; OECD AI Principles
Plain-language explanation
Open-weight models are sometimes loosely called "open source", but the terms differ: releasing weights is not the same as releasing the training data and code needed to reproduce the model. Open weights bring governance trade-offs — they enable scrutiny, customisation, and reduced vendor lock-in, but also make it harder to enforce safety guardrails or restrict misuse once the weights are distributed. This tension is central to current policy debates about how to regulate the most capable models.
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