The client first sends a request with an
Accept-Encoding header that indicates it supports gzip:
GET / HTTP/1.1\r\n Host: www.google.com\r\n Accept-Encoding: gzip, deflate\r\n \r\n
The server may then send a response with a compressed response body and a
Content-Encoding header that specifies that gzip encoding was used::
HTTP/1.1 200 OK\r\n Content-Encoding: gzip\r\n Content-Length: XX\r\n \r\n ... compressed content ...