Magento's highly modular structure is a result of several open source technologies embedded into a stack. These open source technologies are composed of the following components:
PHP: PHP is a server-side scripting language. This book assumes that you have advanced knowledge of the object-oriented aspects of PHP, which is often referred to as PHP OOP.
Coding standards: Magento puts a lot of emphasis on coding standards. These include PSR-0 (the autoloading standard), PSR-1 (the basic coding standards), PSR-2 (the coding style guide), PSR-3, and PSR-4.
Composer: Composer is a dependency management package for PHP. It is used to pull in all the vendor library requirements.
CSS: Magento supports CSS3 via its in-built LESS CSS preprocessor.
jQuery: jQuery is a mature cross-platform JavaScript library that was designed to simplify the DOM manipulation. It is one of the most popular JavaScript frameworks today.
RequireJS: RequireJS is a JavaScript file and module loader. Using a modular script loader such as RequireJS helps improve the speed and quality of code.
Third-party libraries: Magento comes packed with lot of third-party libraries, with the most notable ones being Zend Framework and Symfony. It is worth noting that Zend Framework comes in two different major versions, namely version 1.x and version 2.x. Magento uses both of these versions internally.
Apache or Nginx: Both Apache and Nginx are HTTP servers. Each has its distinct advantages and disadvantages. It would be unfair to say one is better than another, as their performance widely depends on the entire system's setup and usage. Magento works with Apache 2.2 and 2.4 and Nginx 1.7.
MySQL: MySQL is a mature and widely used relational database management system (RDBMS) that uses structured query language (SQL). There are both free community versions and commercial versions of MySQL. Magento requires at least the of MySQL Community Edition version 5.6.
MTF: Magento Testing Framework (MTF) delivers an automated testing suite. It covers various types of tests, such as performance, functional, and unit testing. The entire MTF is available on GitHub, which can be viewed by visiting https://github.com/magento/mtf as an isolated project.
Different pieces of technology can be glued into various architectures. There are different ways to look at the Magento architecture—from the perspective of a module developer, system integrator, or a merchant, or from some other angle.