From entry persona in glossary Human Computer Interaction the Basics
A persona is a rich description of an individual typically including aspects of their domestic situation, job, education, physical, cognitive and perceptual abilities etc. Alomgside scenarios, personas are used at various stages of the UX design process to capture aspects of real users and ensure that products are appropriate for the range of potential users and situations. They are usually fictional, to protect the privacy of real users, but realistic enough to elicit the designers' social understanding of others; rather like the way we understand characters in a book or film.