You browser reveals a little bit about you when it requests a document from a server. As far as I know, that information is all contained in the environmental variables available to any cgi code, such as this one, which tells you what you are revealing and tells you a bit about the server.

Cookies contain information from a server that has been stored in your filespace. That's another story.

Environment variables have ascii values. A happyface () in the table below represents a null string.

Namevalue
GATEWAY_INTERFACECGI/1.1
HTTP_ACCEPTtext/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
HTTP_ACCEPT_ENCODINGgzip
HTTP_CONNECTIONKeep-Alive
HTTP_HOSTwww.plexoft.com
HTTP_IF_MODIFIED_SINCEThu, 24 May 2018 19:10:38 GMT
HTTP_USER_AGENTCCBot/2.0 (https://commoncrawl.org/faq/)
QUERY_STRING
REMOTE_ADDR54.81.196.35
REMOTE_PORT38680
REQUEST_METHODGET
REQUEST_URI/cgi-bin/informant.cgi
SERVER_ADDR208.185.81.39
SERVER_ADMINwebmaster@plexoft.com
SERVER_NAMEwww.plexoft.com
SERVER_PORT80
SERVER_PROTOCOLHTTP/1.1
SERVER_SIGNATURE
SERVER_SOFTWAREApache/2.2.34 (FreeBSD) PHP/5.2.17 with Suhosin-Patch mod_ssl/2.2.34 OpenSSL/1.0.1u-freebsd