Letter opening is a term used to describe the salutation at the beginning of a letter. It typically includes a greeting and the recipient's name. Common letter openings include 'SLIT, ' 'Sirs, ' and 'DEAR.' SLIT is an informal salutation used when writing to a close friend or family member. Sirs is a formal salutation used when writing to a group of people, such as a business or organization. DEAR is a more formal salutation used when writing to a single person.