RIvers & Temperly (A Practical Guide to the Teaching of English, OUP, 1978, p. 47) list 14 purposes or categories of language use
- establishing and maintaining social relations
- expressing one’s reactions
- hiding one’s intentions
- talking one’s way out of trouble
- seeking & giving information
- learning or teaching others to do or make something
- conversing over the telephone
- solving problems
- discussing ideas
- playing with language
- acting out social roles
- entertaining others
- displaying one’s achievements
- sharing leisure activities