The domain knowledge or specialist perspective a prompt asks the model to adopt.
Expertise in prompting refers to the level and type of knowledge the model is expected to emulate in its answer. A prompt may ask the AI to respond like a lawyer, analyst, editor, teacher, or engineer, depending on the task.
Defining expertise helps shape vocabulary, priorities, and depth. It can make the response more aligned with a professional audience or a specialized use case.
Expertise works best when it is paired with role, context, and output expectations. Simply naming an expert persona without further instruction can still leave too much ambiguity.