There are many other reasons for using language than the following four: to give information to request information to request action to promise something.

For example, we use language
1 to open a conversation with a stranger
A: Nice weather today.
B: Yes. Lovely, but yesterday was awful.
2 to tell an exciting story
I met this very strange fellow on the bus and he...
3 to sell/promote a product
If you are not a member of the club, this will be the only issue of the magazine you’ll receive –and we don’t want that to happen.
4 to defend an opinion
The main reason why charges should be dropped
is that the personal consequences would be….
5 to explain how something works
A tornado is a narrow, violently rotating column of
air that ….
6 to honour a deceased
The distinguished author J.R. died Sunday June 4 at the M Health Centre at the age of …
7 to invite somebody to a function:
Mr and Mrs S request the pleasure of the company of Mr and Mrs W at the official celebration of…
8 to present a fairy-tale
Once upon a time, there was a king who had….