15. An instant messaging communication apparatus, comprising: a central processing unit; an input unit for inputting a first instant message and a first semantic tag for the instant message; a network module for transmitting the input first instant message with the first semantic tag encoded in one of a header and a tail of the first instant message, and receiving a second instant message with a second semantic tag encoded in one of a header and a tail of the second instant message; and a display for displaying a user-interactive user interface, the display being divided into a user input region, a log region and a visual topic structural region; the user input region configured to input the first instant message and the first semantic tag of the first instant message; the log region configured to display an instant message log; and the visual topic structural region configured to display a visual topic structural diagram of the first and second instant messages in the instant message log as constructed according to the first and second semantic tags.
15. An instant messaging communication apparatus, comprising: a central processing unit; an input unit for inputting a first instant message and a first semantic tag for the instant message; a network module for transmitting the input first instant message with the first semantic tag encoded in one of a header and a tail of the first instant message, and receiving a second instant message with a second semantic tag encoded in one of a header and a tail of the second instant message; and a display for displaying a user-interactive user interface, the display being divided into a user input region, a log region and a visual topic structural region; the user input region configured to input the first instant message and the first semantic tag of the first instant message; the log region configured to display an instant message log; and the visual topic structural region configured to display a visual topic structural diagram of the first and second instant messages in the instant message log as constructed according to the first and second semantic tags. 16. The apparatus according to claim 15 , wherein the display displays in the log region, after the user selects the first semantic tag in the visual topic structural diagram, instant messages filtered from the instant message log that are associated with the selected first semantic tag.