An informal letter, also referred to as a friendly letter, is a personal letter written to friends or relatives. There are fewer formatting rules for informal letters than there are for business or formal letters.
An informal letter begins with a heading in the upper right hand corner that contains the sender's address and the date. This is followed by a salutation or greeting followed by the recipient's name and a comma, the letter body, a closing phrase also followed by a comma and the sender's signature. When writing to a very close friend or relative, it is permissible to omit the address in the heading unless it has recently changed. Informal letters share personal and family news, recognize special occasions and offer congratulations, sympathy and thanks.