The document discusses formal invitations. It defines a formal invitation as one that follows established norms and customs in its tone and style. It provides the typical format for a formal invitation, including putting the host's logo or name at the top, extending an invitation to an event, providing event details like date and time, location, and including an RSVP request. It lists some common types of events for formal invitations like school, seminar, or meetings. The document also provides an example of a formal invitation and expressions for making, accepting, and declining an invitation.