1. A reproducing method to reproduce a title that corresponds to an application object of a storage medium, the reproducing method comprising: obtaining title information from an index table to determine the corresponding application object, the storage medium comprising the index table, audio-visual (AV) data, one or more playlist files, one or more program applications, and the corresponding application object, each of the playlist files comprising a playlist, the playlist being information to reproduce the AV data, the program applications providing interactive functions with a user and/or additional functions using the AV data, the corresponding application object comprising management information regarding an application and playlist information; reading the corresponding application object; managing execution of the application based on the management information of the read corresponding application object; and controlling the reproduction of the AV data based on the playlist information of the read corresponding application object, wherein the management information comprises a name of the application, information on a lifecycle of the application, and preload information comprising information on data to be preloaded, and wherein the playlist information comprises a name of one of the playlist files comprising a playlist to be reproduced along with the execution of the application.