Those yellow emoticon faces (aka emoticon) are quite popular among young web users because they help in feeling (expressing emotions) while writing a word of text.
Yahoo! Mail, AOL and Windows Live Hotmail Internet shoppers get great support for emoticon except for some unknown reasons, yet Google has not added smiley to Gmail
If you can not imagine life at the time of Gmail, still, Gmail would still like to see a smile, here is a simple move for you:
All you want to try and can be such a simple drag-n-drop (like adding a signature to Gmail)
Step 1: Open Gmail and type a replacement email message (or reply to the existing one).
Step 2: Open Yahoo! in a very new browser window. Smiley classification and drag any graphic picture into your Gmail editor as you see in the screencast below, even animated emoticons can be inserted into Gmail email.