A business letter is a formal written communication used in professional settings. It typically follows a specific format and is used to convey information, requests, or responses between individuals or organizations. Common types of business letters include cover letters, inquiry letters, and complaint letters. These letters are usually typed on company letterhead and include the sender's and recipient's addresses, a date, a greeting, the body of the letter, and a closing. Proper etiquette and tone are essential, as they reflect the professionalism of the sender and the organization, such as companies or non-profits.