Nominal, expressive, and predicative communications are the three categories of messages. A nominal message names someone or something (e.g., John appears on stage). An expressive message describes a state or action (e.g., John smiles). A predicative message predicts a result of an action (e.g., John will win the game). Within these broad categories, there are several sub-types of messages. A messenger's type of vehicle can determine what kind of message he or she delivers. For example, a person riding a horse is using a means of transportation to deliver a message. The type of message depends on how the horse is being used - as a gift or advertisement. Horses are also used for recreational purposes such as racing - in which case the message delivered is informative rather than expressive or predictive. A letter is an expressive message that uses writing as its mode of expression. It can be as simple as a hand-written note, but most often it is a piece of paper with words printed on it. Letters come in many forms including email, Facebook posts, and Instagram stories. An announcement is a predictive message that uses communication as its mode of expression.