nginx [engine x] is a HTTP server and mail proxy server written by Igor Sysoev.
PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.
Meta descriptions are HTML attributes that provide concise explanations of the contents of web pages. Meta descriptions are commonly used on search engine result pages (SERPs) to display preview snippets for a given page.
A canonical link element is an HTML element that helps webmasters prevent duplicate content issues by specifying the "canonical", or "preferred".