cgit is a web interface (cgi) for Git repositories, written in C. licensed under GPLv2.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
HTTP/2 (originally named HTTP/2.0) is a major revision of the HTTP network protocol used by the World Wide Web.
HTTP/3 is the third major version of the Hypertext Transfer Protocol used to exchange information on the World Wide Web.