Depending on your perspective, emoticons may be one of the most charming aspects of online communication or one of the most annoying. Though internet veterans and texting aficionados may think emoticons are old hat, the linguistics behind them is interesting.

An emoticon (short for emotion and icon) is a facial expression represented by a short combination of letters and other characters you can type on your computer's keyboard. The facial expression is typically, though not always, tilted on its side, like this :-).

The above smiley face, which represents eyes, a nose, and a smiling mouth, was invented in 1982 by Scott Fahlman, currently a research professor specializing in artificial intelligence at Carnegie Melon School of Computer Science.

Its intention then, and its most common use today, is to indicate that you're intending humor. When communicating electronically, without the benefit of tone of voice, facial expressions, and body language, it's all too easy to be misunderstood.

The opposite of the smiley face is the frowny face, often used to indicate empathy or disappointment. Just turn the parenthesis around, as in :-(. Though they're shorthand expressions, the most popular emoticons have been further abbreviated. The smiley face now is more often typed as :).

Today, we're not typically bound by text only, and software has adapted. If you type :) or another recognized emoticon in many word processors, email programs, instant messaging programs, web forums, and online games, the software will automatically convert it into a graphical representation. To convert it back, with Microsoft Word for instance, you hit the backspace key, as I just had to do.

When communicating online, some people prefer abbreviations, using <g> instead of :) to indicate the grin of good intentions. Another similar usage is acronyms, with LOL for "Laughing out loud" to convey that you just laughed at the person's joke or are trying to poke fun at or put someone down, for instance. Literally thousands of these expressions exist, and there are different usage conventions in different parts of the world. People in Scandinavian countries often use =) instead of :) because, on their keyboards, the equal sign and right parenthesis are next to each other. People in Japan and other East Asian countries prefer emoticons that can be understood straight up, without tilting your head to the left, as in (^_^) instead of :).

This multiplicity of possibilities can lead to the opposite of what you're intending, causing confusion rather than preventing misunderstanding if those you're communicating with don't know the particular emoticon.

As with jargon, some people use emoticons to show that they're in the know or that they're part of the "in" group. This also can backfire. Newcomers tend to use too many of them, which just labels them as newbies.

As a result of these negatives, some people hate emoticons. One frequently repeated sentiment is that emoticons are a lazy shortcut to good writing and that if Ernest Hemingway didn't need them, neither should we. But the reality is that few people write like Hemingway.

We often think of emoticons and similar expressions as modern, but they're not. Telegraph operators in the mid-19th century used abbreviations such as IMHO ("In my humble opinion") and FWIW ("For what it's worth") when communicating among themselves, according to the 1998 book The Victorian Internet by Tom Standage. Later teletype operators used emoticons when chatting. With both, as with the internet today, it was to save time.

Though they haven't yet, some emoticons may someday become as accepted as exclamation points and question marks. The exclamation point was introduced in English printing only in the 15th century. As with emoticons, the exclamation point's usage varies in different parts of the world. In French and German, for instance, it can be used after a nonexclamatory request. The question mark came into being in its present form in the 13th century.

But there's no guarantee that emoticons will go mainstream. In the 19th century, the "irony mark," a small, elevated, backward-facing question mark, was proposed to signify that a sentence has a secondary meaning, such as irony or sarcasm. It never caught on.

Emoticons are used today because they serve a need. But it's clear that emoticons are inappropriate in many situations, in buttoned-down business writing, for example-using them there won't be received well. Probably the best advice for the use of emoticons in online communication is to follow the conventions of those you're communicating with, making sure your readers understand what you're trying to communicate.