Knowledge of business letter etiquette is essential for anyone in or entering the workplace. Professional types of correspondence such as letters of application, sales letters and letters of reference differ from friendly letters in that they must follow a specific format and should never include informal or slang language. The seven parts of a business letter include: the heading, date, address of recipient, salutation, body, complimentary close and signature.

Heading

Most professional business correspondence is printed on a letterhead template. A letterhead contains the company name, address and contact information. An individual may also create a letterhead that contains his name and personal contact information. While some individuals may choose not to create a formal letterhead, it is always necessary to include a header with the sender's information.

Date

Simply put, the date is the day the letter is sent. The most commonly used date format is: June 21, 2011. Do not abbreviate the month and always include all four digits of the year.

Address

This is the address of the recipient. If applicable, the first line in the address block should include the recipient's name and title, and the second line should state the recipient's company or business. The third and fourth lines are designated for the actual address. For example:

Mr. John Doe, Director of Sales The Sales Firm 123 Main Street Townsville, AR 45678

Salutation

Different circumstances determine which salutation or greeting is most appropriate. Use "Dear" when the recipient's name or title is known. Examples include "Dear Mr. Doe" or "Dear Sales Director." When the name or title is unknown, use "To Whom It May Concern." Always punctuate the salutation of a business letter with a colon instead of a comma.

Body

The body is the longest part of a letter and is usually divided into three subcategories: introduction, main content and summary. The introductory paragraph states the purpose of the letter. The main content conveys all necessary detailed information and has no set length requirements. The last paragraph summarizes the information provided, restates the letter intent and offers either instructions or an inquiry regarding follow-up correspondence.

Complimentary Close

The complimentary close is a word or short phrase that basically means "goodbye." "Sincerely" is the most common closing remark. Others include "cordially," "best wishes," and "best regards." The complimentary close can vary in degrees of formality and is dependent upon the relationship between the sender and recipient.

Signature

In letters that are sent via email, the signature is simply the sender's name and title typed immediately below the complimentary close. When a letter is mailed, faxed or hand-delivered, however, there should be a large enough space below the closing and above the typed name and title for the sender to provide her written signature.