HTTP Upgrade Header - HTTP/2

   The HTTP Upgrade mechanism is used to establish HTTP/2 starting from plain HTTP. The client starts an HTTP/1.1 connection and sends an Upgrade: h2c header. If the server supports HTTP/2, it replies with HTTP 101 Switching Protocol status code. The HTTP Upgrade mechanism is used only for cleartext HTTP2 (h2c). In the case of HTTP2 over TLS (h2), the ALPN TLS protocol extension is used instead.

Vary Header Accept-Encoding

   The Accept-Encoding request HTTP header advertises which content encoding, usually a compression algorithm, the client is able to understand. Using content negotiation, the server selects one of the proposals, uses it and informs the client of its choice with the Content-Encoding response header.

Character Encoding :UTF-8

   This website is using UTF-8 character encoding in HTML , character encoding is used to represent a repertoire of characters by some kind of encoding system.

Gzip Content-Encoding

   The Content-Encoding entity header is used to compress the media-type. When present, its value indicates which encodings were applied to the entity-body. It lets the client know how to decode in order to obtain the media-type referenced by the Content-Type header.