Communication is constantly adapting to new technology. From letters, telephones and faxes to email, text messaging and social media, communication has evolved rapidly.

Think about it. Acronyms are now being used as whole messages LOL for laughing out loud. Hashtags are ubiquitous #everywhere. And emoticons are now supplementing feelings and emotions — .

Communication styles vary from person to person, but when dealing with business communication, there are certain guidelines that professionals should follow. Mainly, your writing should be professional.

But what does "professional" mean?

Professional in terms of communication used to mean using correct punctuation and grammar, along with appropriate vocabulary. Pretty simple. But, just like everything else, professional business communication is changing.

So, is that appropriate to send to a co-worker? A business partner with whom you have a strong relationship? Your boss? A client?

There is no one correct answer to this question. It is all circumstantial. But here is some advice to help you make the best decision when writing your next email.

To start, you must understand how the written communication of emails is understood.

"There's a negativity bias to email at the neural level. In other words, if an email's content is neutral, we assume the tone is negative," according to Daniel Goleman, author of "Social Intelligence."

Having a neutral message interpreted as negative can have a detrimental effect on a relationship professional or personal. So how do we infuse emotion into emails? As electronic communication has become ubiquitous, we've learned that emoticons can do a lot to help recipients understand the email's true tone.

Scientific evidence has even proven the smiley face to be effective in portraying emotion in written communication. According to Social Neuroscience, researchers have shown that when a person views a smiley face on an electronic device, the same part of the brain is activated that is activated when seeing a real person's face.

However, emoticons are not always appropriate, and not everyone uses them. Some still view them as childish and unprofessional.

How are you supposed to determine when, where and with whom they are appropriate? I asked a variety of professionals their opinions on emoticons and the use of them in professional communication to help clarify this intriguing question.

Here are some of their responses:

Kathleen Goodner, communications manager for Washington State Pharmacy Association:

"It really depends on my relationships, audience and the tone of the message. For instance, I stay away from using them in our formal communications ... I even stay away from using them on social media. While I can keep our wording light in nature, emoticons are not appropriate.

"I also don't use emoticons when conversing with people outside of my direct co-workers in general. If I have an established personal/working relationship with the person I am talking to, and it's OK to be more casual, I may throw a smiley face in here and there, but that's it. I don't think the wide array of emoticons that are available are appropriate for business communication in general I think it sends the wrong message/perception.

"As for co-workers, we are small group and know each other well and have established a really good work ethic, so I will throw one in every once in a while. We use Skype a ton, and sometimes it's kind of fun to use them there, but not all the time."

Joshua Viau, attorney-at-law for Fisher & Phillips in Atlanta:

"I never use emoticons in any part of my business communications, including clients, co-workers or superiors. In fact, I rarely use them in my personal communications. The only time I use emoticons at all is in text messages with family members — and even that is rare.

"I just do not feel that they are necessary or appropriate in professional communications. Even if the nature of the business communication is informal and lighthearted, using an emoticon takes it too far. I believe that it also sends the wrong message regarding your focus. If you have time to locate and attach emoticons to a work email, you must not be busy enough.

"I am a lawyer and frankly, I cannot imagine hiring a lawyer who sends an email using emoticons."

Marilyn Mages, communications manager for the Society for Academic Emergency Medicine:

"I only use emoticons in short bursts. I use them only with friends or co-workers who I feel close with. I do not believe that they have a place in the office because of professional issues. Using them doesn't make me look down on the person, but as a communications manager, it is important to be as professional as possible."

As shown by these responses, the opinion of emoticons varies. However, it also shows that emoticons are becoming more accepted in the business world. Even those who do not use emoticons see the changing acceptance of them.

Throughout all of the answers I received, there were a few topics that seemed to come up often.

First was the fact that the use of emoticons is typically associated with a younger individual. However, this is not always the case.

"At first I assumed it would follow age/title, but that turns out not to be the case for me," said Valerie Hunt, a fellow editor at MultiBriefs. "I have a contact who's a VP in her 50s who uses them, and others who are entry-level young professionals who don't."

Another common topic: Receiving an email with an emoticon makes the recipient feel like the sender is friendlier and more understanding they are just regular people, too.

"I feel like this puts the contact at ease and lets them know that they are dealing with someone who is on their team," said Brie Ragland, another fellow editor at MultiBriefs.

The last thing you want to do with an email is make the person feel like he/she is being attacked or looked down upon. Throw in a smiley face, and you show the recipient that the message is not meant to be perceived in a negative way.

Even though there are many factors pointing to widespread acceptance of emoticons, there are still circumstances where emoticons are not OK. In industries where professionalism is still key healthcare, law, government emoticons and other new forms of quick communication are not considered acceptable.

You must know who you are communicating with before you determine your communication style. You have to be cautious when using emoticons, but they can help build better, stronger relationships if used correctly.

My best advice: If you are unsure whether is acceptable, simply wait until the other person uses an emoticon before using one yourself.