Fans are just what they sound like - they are fans of your team! The fans list is a perfect place for those people who want to stay updated about events but do not fall into the parent, player, coach, or manager categories (such as family members and alumni) . Fans are not roster members, they reside on their own list on the fans page. If you want, you can turn on the fans widget and display your fans on the homepage.
Since Fans are not part of the actual rosters, there will be features that are not available to them. One feature is the Subscribe Button on their personal Calendar where they can sync their personal calendar to calendar applications. They may be able to be a part of the team's communications if you included Fans when sending your communications.