Facebook emoticons refer specifically to any emoticons that are supported by Facebook's Facebook Chat feature. Any emoticon can be typed out in a Facebook Chat message, but only those that are supported will appear as corresponding images. Facebook is continuously updating its list of recognised emoticons in an effort to make as many as possible available to its users.
Particularly in the context of instant messaging and social networking posts, emoticons are used to textually represent the tone of the statement preceding it or the mood of the writer. In some cases, abbreviations can be considered emoticons as well. For example, IMHO (short for "In My Humble Opinion") is referred to as an emoticon because it suggests a certain tone. Emoticons can express emotions ranging from happiness and sadness to anger and confusion.
Facebook Chat is an instant messaging feature provided by Facebook for its users. It is the only feature within the Facebook site that will translate certain emoticons into corresponding icons. As of May 2011, it is only able to recognise a small number of the dozens of emoticons that have been defined. However, regular updates and user feedback help to mitigate the problem. Emoticons can be typed out in other sections of Facebook, but they will always appear exactly as typed.
Most of Facebook's supported emoticons are also referred to as smileys. This is because, with a few exceptions, most emoticon icons are variations on a basic smiley face design. Variations include a basic smile, a grin, a wink, a gasp, a frown, a kiss, a crying face, an angry face, an angel, a devil and even a smiley face wearing sunglasses. There are also several non-smiley emoticons, including a robot head and a heart.
Emoticon meanings are reflected in the expressions they represent. It is for this reason that they are often used to provide context to a written statement that could be taken in several ways. The emotion expressed by the emoticon tells the reader how to interpret the tone of the message and helps to avoid problematic misunderstandings. It is much quicker to type out an emoticon than it is to textually explain your mood in a short message.