In academics, formal and informal communications are commonly used in the context of organizational communications, an area of study that examines interactions among people within any organization. This does not always refer to a company or business, however; family or social units have their own organization, and communication flows upwards, downwards or horizontally among peers or equals. Informal methods are more relaxed in structure and tone than formal methods.
You are communicating via a formal method of communication if you are writing a business letter, filling out a job application or complaint form, sending a business fax, composing a business email or even using Morse code. There is a specific structure to the communication. In companies, your written job description is a type of formal communication, as are internal memoranda.
If you give an oral presentation to your manager, clients or prospective customers, you are engaging in formal oral, or verbal, communication. This is also true for business meetings following an agenda, telephone conference calls, press conferences and job interviews.
If you write a personal note to a friend, or include one or two handwritten lines on a card to send with flowers to your mother, you are engaging in informal communication. Other examples include love letters, personal birthday cards, friendly or anecdotal emails, or even writing a note to your spouse on the bathroom mirror.
If you engage in gossip with your friends, you are using an informal verbal method of communicating; in your office you might call it a “grapevine.” Scolding your children, phoning your mother on Mother’s Day or calling the kids inside for dinner are all informal verbal communication methods.