A letter which is not used for personal purposes and is written in a specific format with a very formal language and has a specified and strategised organisation of writing style is known as a formal letter. These letters are thereby not used as family letters, or a letter to friends or cousins, siblings and relatives. Generally, we write such kinds of letters on official platforms including writing a letter to the principal in the school, to the higher delegates in the office, letters to the managers and HR, and an appointment letter to the employee.