In simple terms:

“Open weights” refer to publicly shared, downloadable versions of a trained AI model, especially the parts that let the model actually work—its internal “knowledge” learned during training.

Think of it like sharing the brain of the AI, not just the name or how to talk to it.

What Exactly Are “Weights”?

When an AI model is trained, it doesn’t memorize facts. Instead, it adjusts millions (or billions) of numerical values called weights that help it make decisions.

Imagine a big machine full of knobs. During training, the AI learns to turn the knobs to the right positions so it can:

• Translate languages
• Write poems
• Detect objects in photos
• Or anything else it’s trained for

These knob settings are the weights.

Open Weights vs Closed Weights

Feature	Open Weights	Closed Weights
Access	Free to download	Kept secret
Use	Anyone can fine-tune or use	Only the company controls it
Examples	Meta’s LLaMA, Mistral, Falcon	OpenAI’s GPT-4, Anthropic’s Claude
Pros	Transparency, innovation	Controlled release, monetization

Why Do Open Weights Matter?

• Innovation & Research – Developers and researchers can build on top of existing models.
• Fine-Tuning – You can tweak the model to make it good at specific tasks (like legal writing or customer service).
• Transparency – You can inspect how the model works and test for bias or safety issues.
• Offline Use – You don’t need to connect to the cloud or pay a provider. You can run the model locally.

What Can You Do With Open Weights?

Here are beginner-friendly uses:

• Use open-weight LLMs (like LLaMA 3, Mistral, Phi-3) in apps, chatbots, or websites
• Fine-tune them on your company data to make a specialized assistant
• Run private models offline for extra security or speed
• Learn how AI models work by experimenting with the actual parameters

Where Do You Get Open Weights?

• Hugging Face – the biggest library of open models
• GitHub Repos from Meta, Mistral, EleutherAI, etc.
• Ollama – lets you run open-weight LLMs easily on your computer

Real World Examples

Company	Model Name	Open?
Meta	LLaMA 2, 3	Yes
Mistral	Mistral 7B, Mixtral	Yes
OpenAI	GPT-4	No
Google	Gemini	No
Stability AI	Stable Diffusion	Yes

Gotchas and Limitations

• Open doesn’t mean do anything – most models still have licenses.
• You may need strong GPUs or cloud servers to run large models.
• Not all open-weight models are as powerful as closed ones like GPT-4 (yet).

Final Thoughts

Open weights are a huge part of the open-source movement in AI. They allow anyone to build, innovate, or learn without needing a billion-dollar AI lab.

If you’re just getting started, try running a small model like:

• Phi-3-mini
• Gemma
• LLaMA 3 8B

Using tools like Ollama or Hugging Face Transformers, you can start experimenting today.