The document discusses different types of letters that may be used in a job search or employment process. It identifies 7 types of letters: application/cover letters, appreciation/thank you letters, prospecting letters, networking letters, acceptance letters, withdrawal letters, and rejection letters. It then provides examples of common purposes for business or professional letters and guidelines for an effective letter, such as identifying the purpose, organizing content, being professional, addressing the reader, being succinct and positive, catering to the reader's interests, and signing and keeping a copy.