The most important category of icons is emotion icons. This is because the icons itself are used to indicate the emotions of the person over the instant messenger conversations and e- mail conversations. So emotion icons can do the job easily. Since the instant messenger conversations and email conversations do not involve face to face contact. There are lots of chances for the person at the receiving end to misinterpret the messages. This can be avoided by adding an icon from the range of emotion icons to the message. So the receiver will have clear picture of the emotion of the sender.