The instruction "You are a lawyer" is a classic example of assigning aPersonato an AI model. In prompt engineering, a persona is a specified role or identity that the AI is asked to adopt. This technique is highly effective because it triggers the model to prioritize certain linguistic patterns, professional jargon, and specialized knowledge bases associated with that specific role. By telling the AI to act as a lawyer, the user is signaling that the tone should be formal, the reasoning should be analytical, and the output should reflect legal standards and structures.

Assigning a persona helps narrow the "probabilistic space" of the AI's responses. Instead of providing a generic answer, the model will attempt to provide an answer that a legal professional would likely give. This is different from "Instructions," which tell the AIwhat to do(e.g., "Write a contract"), or "Context," which provides thebackground facts(e.g., "This is for a small business in Ohio"). The persona provides thevoice and perspectivethrough which the information is filtered. Utilizing personas is a core strategy in prompt engineering to ensure that the output matches the professional or creative expectations of the user.