Personas are humanlike descriptions of customer segments. Just like customer segments, you can use the persona technique to divide your overall market into smaller subset that you can then examine individually.
In practice, the best way of using personas for customer segmentation is to apply a technique of data-driven persona creation, such as automatic persona generation. Using this approach, you can create an arbitrary number of personas from your source data; e.g., 5, 10, 50, or 100 personas.
If you are interested in learning more, just contact the persona team!