SPF

   The Sender Policy Framework (SPF) is an email-authentication technique which is used to prevent spammers from sending messages on behalf of your domain. With SPF an organisation can publish authorized mail servers.

SEO Robots : Allow to index and follow website links

   Meta robots tag is a tag that tells search engines what to follow and what not to follow.

Server partial requests support

   The Accept-Ranges response HTTP header is a marker used by the server to advertise its support of partial requests. The value of this field indicates the unit that can be used to define a range.

Cloudflare

   Cloudflare, Inc. is an American web infrastructure and website security company, providing content delivery network services, DDoS mitigation, Internet security, and distributed domain name server services

Viewport - Width

   The viewport is the user`s visible area of a web page. The viewport varies with the device, and will be smaller on a mobile phone than on a computer screen. Before tablets and mobile phones, web pages were designed only for computer screens, and it was common for web pages to have a static design and a fixed size.

Viewport - initial-scale

   The viewport is the user`s visible area of a web page. The viewport varies with the device, and will be smaller on a mobile phone than on a computer screen. Before tablets and mobile phones, web pages were designed only for computer screens, and it was common for web pages to have a static design and a fixed size.

Chunked transfer encoding

   Chunked transfer encoding is a streaming data transfer mechanism available in version 1.1 of the Hypertext Transfer Protocol (HTTP). In chunked transfer encoding, the data stream is divided into a series of non-overlapping "chunks"