Glossary · 3 · Working with models: prompts and context
System prompt
Also known as: System message, System instructions, Custom instructions
A system prompt is the standing instruction that an application gives a language model before any user input — defining its role, tone, rules, knowledge boundaries and output format for the whole conversation. Users usually don’t see it.
- Intermediate
- Technical writers
- Technical project managers
- Developers
In one sentence
System prompts explained: the hidden standing instructions that define an AI assistant’s role, tone and rules — and who should write them.
Example
The system prompt of a documentation assistant says: “Answer only from the provided documentation. If the answer isn’t there, say so and link to support. Never give torque values from memory.”
Why it matters on your learning path
- Technical writers: Writing and reviewing system prompts is content work: it defines the voice and boundaries of every answer.
- Technical project managers: The system prompt is a key control; changes should go through review and testing.
- Developers: Keep system prompts in version control and don’t rely on them as a security boundary — see prompt injection.