WordPress (WP, WordPress.org) is a free and open-source contentcontent management system (CMS) written in PHP and paired with a MySQL or MariaDB database. Features include a plugin architecture and a template system, referred to within WordPress as Themes. WordPress was created as a blog-publishing system but has evolved to support other web content types including more traditional mailing lists and forums, media galleries, membership sites, learning management systems (LMS), and online stores. One of the most popular content management system solutions in use, WordPress is used by 42.8% of the top 10 million websites as of October 2021
“WordPress is a factory that makes webpages” is a core analogy designed to clarify the functions of WordPress: it stores content and enables a user to create and publish webpages, requiring nothing beyond a domain and a hosting service.
WordPress has a web template system using a template processor. Its architecture is a front controller, routing all requests for non-static URIs to a single PHP file which parses the URI and identifies the target page. This allows support for more human-readable permalinks.
WordPress users may install and switch among different themes. Themes allow users to change the look and functionality of a WordPress website without altering the core code or site content. Every WordPress website requires at least one theme to be present. Themes may be directly installed using the WordPress “Appearance” administration tool in the dashboard, or theme folders may be copied directly into the themes directory. WordPress themes are generally classified into two categories: free and premium. Many free themes are listed in the WordPress theme directory (also known as the repository), and premium themes are available for purchase from marketplaces and individual WordPress developers. WordPress users may also create and develop their own custom themes.
WordPress plugin architecture allows users to extend the features and functionality of a website or blog. As of May 2021, WordPress.org has 58,463 plugins available, each of which offers custom functions and features enabling users to tailor their sites to their specific needs. However, this does not include the premium plugins that are available (approximately 1,500+), which may not be listed in the WordPress.org repository. These customizations range from search engine optimization (SEO), to client portals used to display private information to logged-in users, to content management systems, to content displaying features, such as the addition of widgets and navigation bars. Not all available plugins are always abreast with the upgrades, and as a result, they may not function properly or may not function at all. Most plugins are available through WordPress themselves, either via downloading them and installing the files manually via FTP or through the WordPress dashboard. However, many third parties offer plugins through their own websites, many of which are paid packages.
Web developers who wish to develop plugins need to learn the WordPress hook system which consists of over 2,000 hooks (as of Version 5.7 in 2021) divided into two categories: action hooks and filter hooks.
Plugins also represent a development strategy that can transform WordPress into all sorts of software systems and applications, limited only by the imagination and creativity of the programmers. These are implemented using custom plugins to create non-website systems, such as headless WordPress applications and Software as a Service (SaaS) products.
Plugins also could be used by hackers targeting the site that use WordPress, as hackers could exploit bugs on WordPress plugins themselves instead of exploiting the bugs on WordPress itself.