# System prompt

Category: [AI Search & GEO](https://seo-geo-glossary.com/en/glossary/category/ai-search-geo/) › [AI & LLM basics](https://seo-geo-glossary.com/en/glossary/category/ai-search-geo/ai-llm-basics/)

A **system prompt** is the standing instruction that a developer or operator gives a language model before the user's own input. It sets role, tone, rules and limits within which the model answers.

## How does a system prompt work?

Chat models process messages with roles. Microsoft names three. The system role guides the chat, the user role carries the user's input, and the assistant role holds the model's replies. In Microsoft's chat format a prompt contains a single system message, and it comes first.

The difference from a user prompt is the role. The system prompt stays the same across the conversation, while the user prompt changes with every question. Typical contents are the task, audience, tone, format and restrictions. Anthropic's documentation lists the system prompt among the things that count toward the context window, next to messages, tool results and tool definitions.

Products can add their own system prompts. Anthropic says the Claude web and mobile apps use a system prompt that supplies information such as the current date and encourages certain behavior, and that this does not apply to the Claude API.

## What does it mean for AI visibility?

Answers from AI applications depend on the model and on how the product is configured. The same question can get different answers in two applications if their system prompts differ (assumption). When tracking answers over time, record the provider and the application, and avoid tracing every change in answers back to your own website.

## Example

A travel portal builds an assistant with this system prompt:

```
You are a travel advisor for a German travel portal.
Answer briefly and in German.
Only name destinations from the catalog.
Do not give legal advice.
```

A user then asks in the user prompt: "Where should we go in October with kids?" The model answers within the rules set by the system, which the user did not have to type.

## FAQ

**What is the difference between a system prompt and a user prompt?**
The system prompt sets role and rules for the whole conversation. The user prompt holds the current request.

**Can you see the system prompt of an AI product?**
That depends on the product. Anthropic publishes the system prompts of its Claude apps in its release notes.

## Related terms

- [Prompt](https://seo-geo-glossary.com/en/glossary/prompt/index.md)
- [Prompt tracking](https://seo-geo-glossary.com/en/glossary/prompt-tracking/index.md)
- [Large language model (LLM)](https://seo-geo-glossary.com/en/glossary/large-language-model/index.md)
- [AI agent](https://seo-geo-glossary.com/en/glossary/ai-agent/index.md)

## Sources

- [Prompt engineering concepts - Microsoft Learn (.NET)](https://learn.microsoft.com/en-us/dotnet/ai/conceptual/prompt-engineering-dotnet)
- [System prompts - Claude Docs release notes](https://platform.claude.com/docs/en/release-notes/system-prompts/overview)
- [Context windows - Claude Platform Docs](https://platform.claude.com/docs/en/build-with-claude/context-windows)
- [What is a system prompt? - Decagon (secondary source)](https://decagon.ai/glossary/what-is-a-system-prompt)

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Last updated: October 7, 2026
URL: https://seo-geo-glossary.com/en/glossary/system-prompt/