A user terminal device is provided. The user terminal device includes a storage configured to store a plurality of applications, a memory configured to copy the plurality of applications stored in the storage, a controller configured to, in response to a source application and a target application being selected from a plurality of applications copied into the memory and a data share function being selected, convert data of the source application into a serialized stream and provide the serialized stream to the target application. Therefore, data is efficiently shared between applications.