PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.
Open graph description entity tag
Meta Keywords are a specific type of meta tag that appear in the HTML code of a Web page and help tell search engines what the topic of the page is.
This page contains a meta robots tag which tells search engines and robots to index or not index the page.
The http-equiv attribute provides an HTTP header for the information/value of the content attribute. The http-equiv attribute can be used to simulate an HTTP response header.