This document provides guidance on how to write effective business letters. It begins by outlining the objectives of being able to explain the importance of business letters, describe different types of business letters, comprehend and apply techniques for writing business letters, and write a reply/response letter. It then covers topics like the reasons for writing business letters, common types of business letters, the components and formatting of a business letter, sample expressions, quick tips, and proofreading best practices. Examples are provided throughout to illustrate concepts like letter components, formats, and a sample complaint letter.