nginx [engine x] is a HTTP server and mail proxy server written by Igor Sysoev.
Phusion Passenger - a.k.a. mod_rails or mod_rack - is a web server and application server, designed to be fast, robust and lightweight. Administration tools allow you to gain insight into web application operations and server performance.
Ruby on Rails is an open-source web framework that is optimized for programmer happiness and sustainable productivity. It lets you write beautiful code by favoring convention over configuration.
UTF-8 (8-bit UCS/Unicode Transformation Format) is a variable-length character encoding for Unicode. It is the preferred encoding for web pages.
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.
Sites who has this tag are verfied by google to use WebMaster tools
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.