What is a Persona?
A persona is a fictional but research-grounded archetype of a user — name, role, goals, frustrations, context — that keeps the team designing for humans instead of the abstract "user." Stories gain teeth when written against personas: "As Amira, a dispatcher juggling 40 trucks…" beats "as a user…" every time.
Good personas come from real user research; personas invented in a conference room are fiction wearing a lab coat.
Worked example
A field-service app team maintains three personas: "Dev the veteran technician" (gloved hands, bright sunlight, hates typing), "Amira the dispatcher" (two monitors, keyboard-speed everything), "Priya the regional manager" (reads reports on a phone between meetings). When someone proposes a text-heavy form for technicians, Dev's gloves veto it before a single user has to.