Prompting glossary
System prompt
Standing rules that apply to the whole conversation.
What it means
A system prompt sets the role and the ground rules before any individual request: who the assistant is, what it must always do, what it must never do. In everyday chat tools this is the custom instructions or project instructions area.
Also called
custom instructions
How to use this in practice
Knowing the word is the easy half. The useful half is writing the instruction so the AI does not have to guess: say who it should act as, give it the background it cannot know, state the outcome you want, set the limits, and name the format the answer should come back in. That is the same structure behind every template in the free prompt library.
Want prompts written for your business instead of definitions?