I first became aware of "smileys" in the late 80s, early 90s as a University student. I was not studying software development, I was just kind of geeky. Eventually I took a single programming course for Pascal and the smiley :) would sometimes appear in source code comments. Obviously this meant to smile - it didn't take a dictionary to figure that out. Oh my, how things have changed.
My memory, going back that far, tells me the nomenclature goes from smiley, to emoticon, to emoji. I will now check if wikipedia agrees. It does not.
Emoji exist in various genres, including facial expressions, common objects, places and types of weather, and animals. They are much like emoticons, but emoji are pictures rather than typographic approximations;
Emoticons were my introduction to this form of expression. Wherein a smiley is just an example. Although my first use of them came in source code, once the Internet became public ("the Information Superhighway" they called it), emoticons showed up on chat platforms like IRC, AOL, Yahoo Messenger, and countless others. It didn't take long before the software proprietors started substituting actual graphic images for the emoticons that people were typing. For example :) became 😀 and :P became 😛
This article will be completed later.... with a bit about Chinese emojis.