All business letters are written to make something happen. They either inform or seek information or action. A business letter that does not seek action is a non-letter and should never have been written.
This article discusses the main types of business letters and their purposes:
Letters of Transmission
These letters, also called "cover" letters accompaniment something that is being sent to someone and explain why and from what the item is being sent. For example, when a company's annual report is distributed, it is usually accompanied by a letter of transmission highlighting several key points in the report and informing recipients that the report is enclosed or attached.
Letters that Inform
As the title suggests, these letters are intended to inform recipients about something. If you have a mortgage, you may have received a letter from your financial institution advising you that your interest rate has increased. This is a common example of a letter that informs.
Requests and Responses to Requests
Businesses write to individuals or businesses requesting a variety of things or events. These letters of request are typically responded to with letters of response.
Letters of Offer and Acceptance
When a person applies for a job and is successful, he or she usually receives a letter of offer outlining the terms and conditions of the job. Letters of Offer are also used for contracts. When a person accepts an offer, a letter of acceptance is used.
Everyone knows what a letter letter is, they need no explanation. If you are like me, you receive far too many of them.
These are not common, but occasionally businesses send letters of condolence to spouses of employees who die, who family members die, or who else run into a sad or difficult time in their lives.
The interesting thing about letters is that each has a different way of being written depending on it's purpose. All should have the three common elements; an opening paragraph explaining what the letter is about, the body with full details, and an action ending asking for something to happen.
When I receive a letter written by someone who has completed a business communication course, I can tell within seconds. Most of the other letters I receive are mediocre at best or poor at worst.
If you are in the business of writing business letters, reports or other documents and have not studied business communication, I strongly suggest you enroll at the earliest or at least read some of the other articles I have written about business communication.