Since MSN Messenger appeared on the market, emoticons have become more popular. Their inclusion in SMS messages and other type of texts can help to express your mood when writing, but since they are only created with text characters their possibilities are limited. That is why, MSN Messenger included emoticons with images and animations.
With emoticons represented as images and animations, expressing things like :-) or :'( has become very popular. No longer is it necessary to use o_O or xD to express surprise or laugh. With these new animated emoticons, the expressions are a lot easier to recognize, and even if they are other shapes, it is a lot easier to recognize a drawing of a heart than <3.