WordPress is a free and open-source content management system (CMS) based on PHP and MySQL. Features include a plugin architecture and a template system. It is most associated with blogging, but supports other types of web content including more traditional mailing lists and forums, media galleries, and online stores.
To function, WordPress has to be installed on a web server, either part of an Internet hosting service like WordPress.com or a computer running the software package WordPress.org in order to serve as a network host in its own right. A local computer may be used for single-user testing and learning purposes.
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 and every theme should be designed using WordPress standards with structured PHP, valid HTML (HyperText Markup Language), and Cascading Style Sheets (CSS).
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, for example via FTP. The PHP, HTML and CSS found in themes can be directly modified to alter theme behavior, or a theme can be a "child" theme which inherits settings from another theme and selectively overrides features
Online stores typically enable shoppers to use "search" features to find specific models, brands or items. Online customers must have access to the Internet and a valid method of payment in order to complete a transaction, such as a credit card, an Interac-enabled debit card, or a service such as PayPal. For physical products (e.g., paperback books or clothes), the e-tailer ships the products to the customer; for digital products, such as digital audio files of songs or software, the e-tailer typically sends the file to the customer over the Internet. The largest of these online retailing corporations are Alibaba, Amazon.com, and eBay
Alternative names for the activity are "e-tailing", a shortened form of "electronic retail" or "e-shopping", a shortened form of "electronic shopping". An online store may also be called an e-web-store, e-shop, e-store, Internet shop, web-shop, web-store, online store, online storefront and virtual store. Mobile commerce (or m-commerce) describes purchasing from an online retailer's mobile device-optimized website or software application ("app").
WordPress themes are generally classified into two categories: free and premium. Many free themes are listed in the WordPress theme directory, and premium themes are available for purchase from marketplaces and individual WordPress developers. WordPress users may also create and develop their own custom themes. The free theme Underscores created by the WordPress developers has become a popular basis for new themes
WordPress' plugin architecture allows users to extend the features and functionality of a website or blog, each of which offers custom functions and features enabling users to tailor their sites to their specific needs. These customizations range from search engine optimization, 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.