SO WHAT'S A PERSONA?
Understanding the People Who Make the Market
ORIGINS
As near as I can tell, Persona is a term conceived by Alex Cowen and he uses it to understand the human elements of a market; it is the first step in his Venture Design Process (VDP). I would encourage you to visit Alex's website for his full discussion on Personas. For my efforts I have used Personas as a means of naming and organizing roles the various stakeholders fill in the market(s) I've identified.
PERSONAS AND STORYBOARDING
Personas are especially helpful to me when I am storyboarding, and storyboarding is a powerful tool for visualizing the relationships that Personas in a particular market share with one another. It's a great way to graphically represent a market and the human roles within that market. In turn, this work helps me develop the role-based questions I can use for Customer Discovery Interviews. The interviews put me in direct contact with the people in those roles, and ultimately help me understand the motivations and needs across Personas.
A COMBINATION
Going back to Michael Gerber and his book E-Myth, and combining it with Alex Cowen's VDP, understanding the motivations and needs of Personas is a powerful mechanism for understanding markets. My hope for this combination would be to validate Commodity worthiness in terms of a marketable Product, and in doing so, create an exceptional brand.