An online game service provider offers several games that registered users can play online. The provider wants to keep track of the games it offers and the players. Each game has a title, description, and an age-related rating. When a user registers for the web site, they provide information about their name, date of birth, and email address. Users sign up for one of the membership types. Membership types differ in terms of a number of games that the user can play, access level etc. The provider wants to keep track of every time a specific user plays a specific game, including the start and the end time. The game provider would like to maintain a list of areas of interest of players that potentially includes multiple values.