8. The method of claim 7 , wherein the comparing of the tags comprises calculating a correlation between the two tags and determining similarity according to the calculated value.
7. A method of recommending digital content to a first user of digital content desiring to be compared to a second user of digital content, the first and second users not authors of the digital content, the method comprising: merging a plurality of tag items included in a profile of the first user of digital content with a plurality of tag items in a profile of the second user of digital content to form a singular tag domain; extracting a preference value related to the digital content of a t least one of the first user and the second user based on a digital content preference of the respective first user and the second user to similar digital content; comparing tags to which preference values are assigned for both users of the digital content; calculating a recommendation value for each of a digital content files by adding all the preference values for the tags that have been compared; and recommending the plurality of digital content files to the first user of digital content in order of decreasing recommendation value.