One sentence describing a feature from the point of view of the person using it: 'As a…, I want…, so that…'.
A user story is a way of writing requirements in people's language rather than technical language. The familiar form is: 'As a receptionist, I want to see today's appointments on one screen, so that I can answer callers quickly.' Three parts: who, what they want, and why. The third is the most important, because it reveals the real goal and may lead to a simpler solution than the one requested.
A feature list like 'appointments screen, search, reports' says neither for whom nor why, so something gets built that is correct in form and useless in practice. Stories keep the conversation about real people and make prioritizing easy: which story, if left undone, stops the work? They are also the best way to describe what you want to an AI builder. You can start with the Product Owner Noura, who turns your answers into a requirements document and a task list. Practical tip: write one story for every role in your system, owner, manager, staff and customer, before thinking about any screen.