Recording medium, method of controlling file of the recording medium, and method and apparatus for reproducing the same

A recording medium, a controlling method of a file of the recording medium, and a reproducing method and device thereof are provided to combine original data recorded on an optical disk with additional data downloaded from an external source, thereby increasing product efficiency as making a user easily use a product. A recording medium includes at least one data area. The at least one data area is composed of original data files, at least one normal file which designates one of the original data files, and at least one remote file which designates at least one additional data file to be downloaded from an external source so that the downloaded file is reproduced. The recording medium further comprises a file system area for storing original file system information. The original file system information consists of ID information which indicates whether the at least one normal file and the at least one remote file are normal files or the remote files, respectively.