1. A method of providing a personalized content in a content providing server, comprising: receiving, from a client, a content request identifying a content category; identifying the client associated with the content request; identifying the content category from the content request; determining if the content category is included in a preference tag associated with the identified client, wherein the preference tag comprises a plurality of hierarchical category identifiers selected from a hierarchical configuration of category identifiers; and in response to the content category being included in the preference tag associated with the identified client, providing personalized content in accordance with the preference tag of the identified client, and in response to there being no preference tag associated with the identified client, providing the personalized content in accordance with preference tags of other clients, using collaborative filtering, wherein providing the personalized content in accordance with the preference tag of the identified client comprises providing the personalized content in accordance with the preference tag that is included in the content category of the identified client using a preference score of the preference tag, wherein the preference score of the preference tag depends on a frequency of client accesses to content objects with the preference tag and on category weight as a function of type of event and tag level of the preference tag, and wherein the personalized content associated with the preference tag and a personalized content associated with a different preference tag of the identified client are provided to the identified client according to a ratio of the preference scores of the preference tags.