Routine business letters are an essential form of communication between businesses and clients. Business letters must be written in a formal, professional tone. There are various types of routine business letters, including requests, replies, and goodwill messages. Key characteristics of effective business letters include clear content, a goodwill tone that emphasizes reader benefits, and correct formatting. The document provides guidelines for writing different types of routine business letters, such as requests, order letters, claim letters, replies, recommendations, and goodwill messages. It stresses the importance of considering the reader's perspective and revising letters thoroughly before sending them.