The document defines letter writing and describes the different types and components of letters. It explains that a letter is a written message used to convey information to those who are distant. There are three main types of letters: personal letters between friends and family, business letters between companies, and official letters for applications and recommendations. All letters include elements like the sender's address, date, recipient's address, greeting, body, closing, and signature. The document also outlines different letter formats and provides examples of components like addresses and closings.