User Modeling in Personalized Service Offering

User modeling is the prerequisite and core technology of personalized service offering.It determines the quality of personalized service.User modeling is divided into five related modules,i.e.,input,output,time characteristic,objects to be modeled and algorithms.The current status of the five modules is reviewed in detail.Input reflects the necessary data source for user modeling.Output is the model representation.Time characteristic means the effective duration of user model and update frequency.Objects to be modeled list the target objects to be included in the user model.Algorithms are applied to transform the input to output.