Personas are used to identify the type of people that use your product so that developers and marketers can visualize them while they work in an effort to meet Joe & Betty’s needs. Some software shops go all out and make posters of their “users” and hang them about.
I have done this some, but not always as we felt the end user was fairly well understood (in Security, or tasked with Six Sigma compliance.) That could be debated of course, but given time and budget I would prefer to focus more on user testing and field studies with real users, if I had to choose.
That said, I did add “User Profiles” into the PentaSafe software product lifecycle as an actual process that had to be completed. Here is what that procedure involved:
Learn how to create Personas from usability.gov