Worth a thousand interpersonal words: Emoji as affective signals for relationship oriented digital communication.

First introduced as a way to provide
nonverbal expression, emoticons are faces made of characters, such as :-) and :( became non-verbal surrogates, providing cues that could not otherwise be conveyed.

People began using emoticons to express affect and to provide an emotional valence advisement for how to interpret the message, to avoid misunderstandings or negative feelings.