Business letters are still perceived as the best method of communication between businesses and their customers, suppliers and job seekers despite emails becoming the most popular method of business communication. They can be solicited, meaning asked for by someone, or unsolicited, meaning the letter is unexpected. Business letters come in five main types, all with different purposes in mind: responding to someone, asking permission for a project, petitioning something, acting as a cover letter, or applying for a job. Knowing the different reasons to write a business letter can help bring success to individuals and companies in business.

Delivering a Response

Business letters can be sent to deliver a response directed at a request for something for which a person has applied. These are usually from a business. Businesses or organizations can respond to an application for a job, a request for funds, a scholarship, or admission to a program. The response can either be bad news, which is usually buried and cushioned between kind, polite words and advice, or good news, which often comes attached with a congratulations and further instructions.

For legal purposes, response letters from businesses are always written as politely as possible so as not to excessively offend anyone.

Asking for Permission for a Project

The purpose of a business letter can include asking the permission of a company to help with any project, such as to allow filming on company property. These types of letter answers the question "is this project reasonable?" to convince the company that if they do not help, they are the ones being unreasonable. If the project is reasonable, included are reasons why it will not hurt the business's reputation, bank account and employees.

A business letter can also ask permission for a project by trying to convince the business that the project is beneficial for it. This occurs by providing background information, history or the kinds of profits the company will gain in return.

Petitioning a Problem that Affects a Group

A business letter can be sent for the purpose of petitioning a problem that affects a group. This letter includes a description of the problem or opportunity, a statement of who it affects and approximately how many people are affected and the location of the problem. If the location is not a specific one, a list of examples may be included. It also describes how pressing the situation is, how many people are affected and how the sender plans to solve this problem – with or without the help of the business – to emphasize that the petition has a real purpose.

Cover Letter for a Resume

A cover letter is a kind of business letter attached to a resume. This purpose of this business letter is to let businesses know the author can speak and write intelligently. It includes relevant education, work experience, and a relation of the author to the reader. This letter's purpose is to state that what the author is sending is a resume and whatever other job application material may be requested (e.g., a sample of writing or design).

Application Letter for a Job

Slightly different from a cover letter, application letters are sent to potential employers to convince them to interview the applicant. Application letters contain a reference to the job being applied for, the sender's qualifications and work experience that relate to the job, contact information, and anything which they would like to state that is not already in their resume. Application business letters are written to convince people to read the applicant's resume and show them positively compared to other candidates.