This document provides information on how to write a business letter, including its definition, parts, styles, and examples. It discusses the key components of a business letter such as the sender's address, date, salutation, body, complimentary close, and signature. It also describes the three main styles of business letters - full block, modified block, and semi block. An example of a business letter in block format is given to demonstrate layout. Finally, it lists and defines different types of business letters such as application letters, order letters, and complaint letters.