This document provides guidance on writing effective letters for business or contractual communication. It outlines the key elements that should be included in a letter such as identifying the sender and recipient, including a reference number and date, stating the subject or purpose, presenting the main body of information, and concluding with any required actions. Follow-up letters should reference earlier correspondence. The document also recommends structuring the letter clearly with sections for an introduction, main points, counterpoints if needed, and a conclusion. Proper formatting and including attachments and carbon copies ensures effective communication.