Role prompting
Also called persona prompting, act as, role play prompting
Telling the AI to act as a particular expert or character, such as an editor or a teacher.
Role prompting gives the model a role to play, such as "You are an experienced tax accountant" or "Act as a sceptical investor". The role acts as shorthand for a whole set of expectations: vocabulary, priorities, level of detail and tone. It is one of the most common prompt techniques and often appears in system prompts.
Roles help most when they change what the model pays attention to. "Act as a security reviewer" pushes a code review toward vulnerabilities; "act as a first-time customer" makes feedback on a pricing page more naive and useful. Roles that also define the audience or the goal, not just a job title, tend to work best.
Roles do not give the model knowledge it does not have. Calling it a doctor does not make medical answers more accurate, and studies on whether expert personas raise accuracy show mixed results. Think of a role as a way to set perspective and style, combined with clear instructions about the task itself.
Example
"You are a demanding editor at a business magazine. Point out the three weakest sentences in this draft and explain why each fails." The role makes the feedback blunt and specific instead of encouraging and general.
Common mistake
Relying on the role instead of instructions. "You are a world-class copywriter" followed by "write an ad" still gives a generic ad. The role sets tone, but the result depends on the details you give: the product, the audience, the length and what to avoid.