In most cases, a letter of interest is a letter written by a potential employee to indicate interest in a job or open position. It can be written or typed, delivered through postal mail, e-mail, interoffice memo, or fax. The letter of interest can be sent in response to a posted job opening, or it can be a query about a job that is not yet available. It is used to introduce the sender, state his or her qualifications and intentions, and usually accompanies a resume and examples of work when applicable. A letter of interest may also be called a prospecting letter, inquiry letter, or interest letter.

Like a postal letter sent to a business associate, a letter of interest usually includes the sender's name, mailing address, city, state, zip code, phone number, and e-mail address. These are usually followed by a date, and then the information of the person receiving the letter, including the name, job title, company, and address of the company. The letter is then addressed as a typical business letter, usually with a Dear Mr. or Dear Ms.

The body of the letter of interest should include information on why the applicant is interested in the company. It should also explain how the company could benefit from having him or her as an employee, and what skills and assets he or she could bring to the company. The letter of interest should include brief details about any relevant job experience and comment on how that experience relates to the position being sought.

A letter of interest may be written in one of a variety of formats and characters. The letter can be loose, laidback, and filled with confidence. It can include humor and personality, and can give the employer a look into what kind of person is writing. These letters can be appropriate for some jobs and some employers, but others may dismiss them as unprofessional.

Conversely, many letters of interest are written as strict business letters: no nonsense and straight to the point. This type of letter often conveys the necessary points the best. It may not stand out with an employer looking for a potential employee with something to set him apart from the field, however.

In many cases, a letter of interest is ended with a phrase similar to the following: "Thank you for your time and consideration. I look forward to hearing from you." These last sentences are used to thank the employer for considering the letter of interest, and to let them know that the applicant expects and is eager to hear from the company about an interview or other kind of follow-up. This is usually followed by a sign-off, a signature, and the typed name.