The informative use of language involves information giving and receiving. The general assumption is that the content is believable and valuable. For example, language is used to offer opinions, give advice, make announcements, lecture, admonish, report news, solicit input or ask questions. Everyday conversations center around information sharing.
Language expresses and evokes ideas, thoughts and feelings. Expressive language may or may not include any real information because the purpose of expressive use of language is to convey emotion. For example, the expression “Yuck” connotes disgust, but the word itself isn't necessarily used to inform. Expressive language in literature, music and the performing arts has the power to inspire and entertain.
Language is used to establish and maintain social order. Directive use of language establishes norms of expected behavior in certain situations. Traffic signs, laws, rules and policies are among the common forms of directive language that promote health and safety in society. “Eat your vegetables” is an example of directive use of language used in informal communication.
In many cases, use of language serves multiple purposes. For example, the statement “Stop that” is both directive and expressive. Yawning and uttering “I’m tired” is informative, expressive, and possibly directive if used to imply that another person should leave because it's late.