As example in the use case
Multiple formats and multilingual site.,
the client sends the request:
curl --location --request GET 'www.museum.example.com/artwork/45' \
--header 'Accept-Language: fr;q=0.9, en;q=0.8, *;q=0.5'
And the server answer with the response:
HTTP/1.1 200 OK
Content-Type: text/html
Content-Language: fr
Vary: Accept-Language
Content-Length: 2487 ...