Linux

Linux is a computer operating system assembled under the model of free and open-source software development and distribution. Linux was originally developed as a free operating system for Intel x86-based personal computers. It has since been ported to more computer hardware platforms than any other operating system. It is a leading operating system on servers and other big iron systems such as mainframe computers and supercomputers. As of June 2013, more than 95% of the world's 500 fastest supercomputers run some variant of Linux, including all the 44 fastest. Linux also runs on embedded systems, which are devices whose operating system is typically built into the firmware and is highly tailored to the system; this includes mobile phones, tablet computers, network routers, facility automation controls, televisions and video game consoles. Android, a widely-used operating system for mobile devices, is built on top of the Linux kernel.

Nginx

Nginx (pronounced "engine-x") is an open source reverse proxy server for HTTP, HTTPS, SMTP, POP3, and IMAP protocols, as well as a load balancer, HTTP cache, and a web server (origin server). The nginx project started with a strong focus on high concurrency, high performance and low memory usage. It runs on Linux, BSD variants, Mac OS X, Solaris, AIX, HP-UX, as well as on other *nix flavors. It also has a proof of concept port for Microsoft Windows. 

Originally, nginx was developed to fill the needs of websites including Rambler, for which it was serving 500 million requests per day by September 2008. According to Netcraft's August 2014 Web Server Survey, nginx was found to be the second most widely used web server across all "active" sites (14.47% of surveyed sites) and for the top million busiest sites (19.60% of surveyed sites). According to W3Techs, it was used by 24.6% of the top 1 million websites, 32.9% of the top 100,000 websites, and by 41.1% of the top 1,000 websites. According to BuiltWith, it is used on 23.8% of the top 10,000 websites, and its growth within the top 10k, 100k and 1 million segments has increased.

Apache

The Apache HTTP Server, colloquially called Apache, is a Web server application notable for playing a key role in the initial growth of the World Wide Web. Originally based on the NCSA HTTPd server, development of Apache began in early 1995 after work on the NCSA code stalled. Apache quickly overtook NCSA HTTPd as the dominant HTTP server, and has remained the most popular HTTP server in use since April 1996. In 2009, it became the first Web server software to serve more than 100 million Web sites.

Apache is developed and maintained by an open community of developers under the auspices of the Apache Software Foundation. Most commonly used on a Unix-like system, the software is available for a wide variety of operating systems, including Unix, FreeBSD, Linux, Solaris, Novell NetWare, OS X, Microsoft Windows, OS/2, TPF, OpenVMS and eComStation. Released under the Apache License, Apache is open-source software.

As of June 2013, Apache was estimated to serve 54.2% of all active Web sites and 53.3% of the top servers across all domains.

Varnish

Varnish is an HTTP accelerator designed for content-heavy dynamic web sites as well as heavily consumed APIs. In contrast to other web accelerators, such as Squid, which began life as a client-side cache, or Apache and nginx, which are primarily origin servers, Varnish was designed as an HTTP accelerator. Varnish is focused exclusively on HTTP, unlike other proxy servers that often support FTP, SMTP and other network protocols.

Varnish is used by a great number of high-profile, high-traffic websites including online newspaper sites such as The New York Times, BBC, The Guardian, The Hindu, social media and content sites such as Facebook, Twitter, Vimeo, Tumblr and many more. Of the Top 10K sites in the web, around a tenth use the software.

Memcache

Memcached is a general-purpose distributed memory caching system. It is often used to speed up dynamic database-driven websites by caching data and objects in RAM to reduce the number of times an external data source (such as a database or API) must be read.

Memcached is free and open-source software. Memcached runs on Unix-like (at least Linux and OS X) and on Microsoft Windows. 

Memcached was originally developed by Danga Interactive for LiveJournal, but is now used by many other systems, including MocoSpace, YouTube, Reddit, Zynga, Facebook, Orange, Twitter, Tumblr and Wikipedia. Engine Yard and Jelastic are using Memcached as part of their platform as a service technology stack and Heroku offers several Memcached services as part of their platform as a service. Google App Engine, AppScale, Microsoft Azure and Amazon Web Services also offer a Memcached service through an API.

RabbitMQ

RabbitMQ is open source message broker software (sometimes called message-oriented middleware) that implements the Advanced Message Queuing Protocol (AMQP). The RabbitMQ server is written in the Erlang programming language and is built on the Open Telecom Platform framework for clustering and failover. Client libraries to interface with the broker are available for all major programming languages.

AMQP

The Advanced Message Queuing Protocol (AMQP) is an open standard application layer protocol for message-oriented middleware. The defining features of AMQP are message orientation, queuing, routing (including point-to-point and publish-and-subscribe), reliability and security.

Puppet

Puppet is an open source configuration management utility. It runs on many Unix-like systems as well as on Microsoft Windows, and includes its own declarative language to describe system configuration.

Puppet is a tool designed to manage the configuration of Unix-like and Microsoft Windows systems declaratively. The user describes system resources and their state, either using Puppet's declarative language or a Ruby DSL (domain-specific language). This information is stored in files called "Puppet manifests". Puppet discovers the system information via a utility called Facter, and compiles the Puppet manifests into a system-specific catalog containing resources and resource dependency, which are applied against the target systems. 

Puppet is used by the Wikimedia Foundation, ARIN, Mozilla, Reddit, Dell, Rackspace, Zynga, Twitter, the New York Stock Exchange, PayPal, Disney, Citrix Systems, Spotify, Oracle, Yandex, the University of California Los Angeles, the University of North Texas, the Los Alamos National Laboratory, Stanford University, Lexmark and Google, among others.

Git

Git is a distributed revision control and source code management (SCM) system with an emphasis on speed, data integrity, and support for distributed, non-linear workflows. Git was initially designed and developed by Linus Torvalds for Linux kernel development in 2005, and has since become the most widely adopted version control system for software development.

As with most other distributed revision control systems, and unlike most client–server systems, every Git working directory is a full-fledged repository with complete history and full version-tracking capabilities, independent of network access or a central server. Like the Linux kernel, Git is free software distributed under the terms of the GNU General Public License version 2.

REST API

Representational state transfer (REST) is an abstraction of the architecture of the World Wide Web; more precisely, REST is an architectural style consisting of a coordinated set of architectural constraints applied to components, connectors, and data elements, within a distributed hypermedia system. 

Web service APIs that adhere to the REST architectural constraints are called RESTful. HTTP based RESTful APIs are defined with these aspects:

• base URI, such as http://example.com/resources/
• an Internet media type for the data. This is often JSON but can be any other valid Internet media type (e.g. XML, Atom, microformats, images, etc.)
• standard HTTP methods (e.g., GET, PUT, POST, or DELETE)
• hypertext links to reference state
• hypertext links to reference related resources

PostgreSQL

PostgreSQL, often simply "Postgres", is an object-relational database management system (ORDBMS) with an emphasis on extensibility and standards-compliance. As a database server, its primary function is to store data, securely and supporting best practices, and retrieve it later, as requested by other software applications, be it those on the same computer or those running on another computer across a network (including the Internet). It can handle workloads ranging from small single-machine applications to large Internet-facing applications with many concurrent users. Recent versions also provide replication of the database itself for security and scalability.

MySQL

MySQL "My S-Q-L", officially, but also called "My Sequel") is (as of March 2014) the world's second most widely used open-source relational database management system (RDBMS). The SQL phrase stands for Structured Query Language. 

Applications which use MySQL databases include: TYPO3, MODx, Joomla, WordPress, phpBB, MyBB, Drupal and other software. MySQL is also used in many high-profile, large-scale websites, including Google (though not for searches), Facebook, Twitter, Flickr, and YouTube.

Drupal

Drupal is a free and open-source content-management framework written in PHP and distributed under the GNU General Public License. It is used as a back-end framework for at least 2.1% of all Web sites worldwide ranging from personal blogs to corporate, political, and government sites including WhiteHouse.gov and data.gov.uk. It is also used for knowledge management and business collaboration.

The standard release of Drupal, known as Drupal core, contains basic features common to content management systems. These include user account registration and maintenance, menu management, RSS feeds, taxonomy, page layout customization, and system administration. The Drupal core installation can serve as a simple Web site, a single- or multi-user blog, an Internet forum, or a community Web site providing for user-generated content.

As of October 2014, there are more than 30,000 free community-contributed addons, known as contributed modules, available to alter and extend Drupal's core capabilities and add new features or customize Drupal's behavior and appearance. The Drupal community has more than 1 million members (as of October 2013) and 31,000 Developers (as of February 2014). Because of this plug-in extensibility and modular design, "The Drupal Overview" on Drupal's Web site describes it as a content management framework. Drupal is also described as a Web application framework, as it meets the generally accepted feature requirements for such frameworks.

Although Drupal offers a sophisticated programming interface for developers, basic Web site installation and administration of the framework requires no programming skills.

Drupal runs on any computing platform that supports both a Web server capable of running PHP (including Apache, IIS, Lighttpd, Hiawatha, Cherokee or Nginx) and a database (such as MySQL, MongoDB, MariaDB, PostgreSQL, SQLite, or Microsoft SQL Server) to store content and settings.

PHP5

PHP is a server-side scripting language designed for web development but also used as a general-purpose programming language. As of January 2013, PHP was installed on more than 240 million websites (39% of those sampled) and 2.1 million web servers.

PHP code can be simply mixed with HTML code, or it can be used in combination with various templating engines and web frameworks. PHP code is usually processed by a PHP interpreter, which is usually implemented as a web server's native module or a Common Gateway Interface (CGI) executable. After the PHP code is interpreted and executed, the web server sends resulting output to its client, usually in form of a part of the generated web page – for example, PHP code can generate a web page's HTML code, an image, or some other data. PHP has also evolved to include a command-line interface (CLI) capability and can be used in standalone graphical applications.

PHP 5 included new features such as improved support for object-oriented programming, the PHP Data Objects (PDO) extension (which defines a lightweight and consistent interface for accessing databases), and numerous performance enhancements. In 2008 PHP 5 became the only stable version under development. Late static binding had been missing from PHP and was added in version 5.3

As of April 2007, over 20 million Internet domains had web services hosted on servers with PHP installed and mod_php was recorded as the most popular Apache HTTP Server module. As of October 2010, PHP was used as the server-side programming language on 75% of all websites whose server-side programming language was known[121] (as of February 2014, the percentage had reached 82%), and PHP was the most-used open source software within enterprises. Web content management systems written in PHP include MediaWiki, Joomla, eZ Publish, SilverStripe, WordPress, Drupal, Moodle, Digg and the user-facing portion of Facebook.

jQuery

jQuery is a cross-platform JavaScript library designed to simplify the client-side scripting of HTML. Used by over 60% of the 10,000 most visited websites, jQuery is the most popular JavaScript library in use today. jQuery is free, open source software, licensed under the MIT License.

jQuery's syntax is designed to make it easier to navigate a document, select DOM elements, create animations, handle events, and develop Ajax applications. jQuery also provides capabilities for developers to create plug-ins on top of the JavaScript library. This enables developers to create abstractions for low-level interaction and animation, advanced effects and high-level, theme-able widgets. The modular approach to the jQuery library allows the creation of powerful dynamic web pages and web applications.

HTML5

HTML5 is a core technology markup language of the Internet used for structuring and presenting content for the World Wide Web. It is the fifth revision of the HTML standard (created in 1990 and standardized as HTML 4 as of 1997) and, as of December 2012, is a candidate recommendation of the World Wide Web Consortium (W3C). Its core aims have been to improve the language with support for the latest multimedia while keeping it easily readable by humans and consistently understood by computers and devices (web browsers, parsers, etc.). 

In particular, HTML5 adds many new syntactic features. These include the new <video>, <audio> and <canvas> elements, as well as the integration of scalable vector graphics (SVG) content (replacing generic <object> tags), and MathML for mathematical formulas. These features are designed to make it easy to include and handle multimedia and graphical content on the web without having to resort to proprietary plugins and APIs. Other new elements, such as <section>, <article>, <header> and <nav>, are designed to enrich the semantic content of documents. New attributes have been introduced for the same purpose, while some elements and attributes have been removed. Some elements, such as <a>, <cite> and <menu> have been changed, redefined or standardized. The APIs and Document Object Model (DOM) are no longer afterthoughts, but are fundamental parts of the HTML5 specification. HTML5 also defines in some detail the required processing for invalid documents so that syntax errors will be treated uniformly by all conforming browsers and other user agents.

Many features of HTML5 have been built with the consideration of being able to run on low-powered devices such as smartphones and tablets. In December 2011, research firm Strategy Analytics accurately forecast sales of HTML5 compatible phones would top 1 billion by 2013.

CSS3

Cascading Style Sheets (CSS) is a style sheet language used for describing the look and formatting of a document written in a markup language. While most often used to change the style web pages and user interfaces written in HTML and XHTML, the language can be applied to any kind of XML document, including plain XML, SVG and XUL. CSS is a cornerstone specification of the web, and almost all web pages use CSS style sheets to describe their presentation.

Unlike CSS 2, which is a large single specification defining various features, CSS 3 is divided into several separate documents called "modules". Each module adds new capabilities or extends features defined in CSS 2, preserving backward compatibility. Work on CSS level 3 started around the time of publication of the original CSS 2 recommendation. The earliest CSS 3 drafts were published in June 1999.

Due to the modularization, different modules have different stability and statuses. As of June 2012, there are over fifty CSS modules published from the CSS Working Group, and four of these have been published as formal recommendations:

• Media Queries
• Namespaces
• Selectors Level 3
• Color

SASS

Sass is a scripting language framework that is interpreted into Cascading Style Sheets (CSS). SassScript is the scripting language itself. SassScript provides the following mechanisms: variables, nesting, mixins, and selector inheritance. Sass consists of two syntaxes. The original syntax, called "the indented syntax", uses a syntax similar to Haml. It uses indentation to separate code blocks and newline characters to separate rules. The newer syntax, "SCSS", uses block formatting like that of CSS. It uses braces to denote code blocks and semicolons to separate lines within a block. The indented syntax and SCSS files are traditionally given the extensions .sass and .scss respectively.

CSS3 consists of a series of selectors and pseudo-selectors that group rules that apply to them. Sass (in the larger context of both syntaxes) extends CSS by providing several mechanisms available in more traditional programming languages, particularly object-oriented languages, but that are not available to CSS3 itself. When SassScript is interpreted, it creates blocks of CSS rules for various selectors as defined by the Sass file. The Sass interpreter translates SassScript into CSS. Alternately, Sass can monitor the .sass or .scss file and translate it to an output .css file whenever the .sass or .scss file is saved.

Node.js

In software development, Node.js is an open-source, cross-platform runtime environment for developing server-side Web applications. Although Node.js is not a JavaScript framework, many of its basic modules are written in JavaScript, and developers can write new modules in JavaScript. The runtime environment interprets JavaScript using Google's V8 JavaScript engine.

Node.js has an event-driven architecture capable of asynchronous I/O. These design choices aim to optimize throughput and scalability in Web applications with many input/output operations, as well as for real-time Web applications (e.g., real-time communication programs and browser games).

The Node.js distributed development project, governed by the Node.js Foundation, is facilitated by the Linux Foundation's Collaborative Projects program.

Corporate users of Node.js software include GoDaddy, Groupon, IBM, LinkedIn, Microsoft, Netflix, PayPal, Rakuten, SAP, Voxer, Walmart, and Yahoo!.

Credit: Wikipedia