1. features
    1. Search Topics from Web
    2. Search Images from Web
    3. Structures
    4. Drilldown &Drilluo
    5. Powerful Filter
    6. Marker
    7. Label
    8. Attachment
    9. Hyperlink
  2. Levels of details
  3. Easy reorganization
  4. Interactive with Internet
  5. Visual connection and comprehension