Communication may be as necessary for human beings to function as water, air or shelter. We are social animals, and without communicating our messages clearly, we may not get what we need to survive. The needed thing could be money (advertising is a method of communication), advice or just emotional support. But the various ways of communication all have their positive -- and negative -- aspects.
Formal communication, such as a certified letter, keeps people at an emotional distance, which can be good or bad. It is good if you don't want to get overly emotional about a matter. It's bad if informal communication would be a faster or easier method of resolving your issue.
Informal communication can be inappropriate for some environments, especially business or legal ones. However, it can be a better way to resolve issues that don't benefit from getting up in a formal resolution process.
Verbal communication allows the speaker to make specific points and expound on any that are unclear. However, it can be hard to prove the communication took place if there is no written record.
Nonverbal communication, such as a hug when someone is sad, can be more effective than all the verbal communication in the world. However, it's not always appropriate to use, especially at work.
Communicating in person offers the recipients undivided attention and lets them know they are important. However, it usually takes more time and effort than an e-mail or phone call.
E-mail is quick, convenient, and these days, ubiquitous in industrialised nations. However, it can be easy to send to the wrong party, or regret messages sent when emotions were running high.
Fax is a fast way to send written communication, but it can be inappropriate for lengthy documents. Faxes can also become easily lost, especially if you work for a large business where these messages come through constantly.
Phone calls allow the personal aspect of hearing an individual's voice, and concerns can be answered faster than by e-mail or fax. However, going over a great deal of written information may require having documents in front both the caller and the receiver -- face-to-face meetings are better for this.
Finally, written communication allows the sender to carefully consider the message before releasing it. Depending on the mode of travel, however, it can take a while before reaching the recipient.