WordPress is a free and open-source blogging tool and a content management system (CMS) based on PHP and MySQL. Features include a plugin architecture and a template system. WordPress was used by more than 23.3% of the top 10 million websites as of January 2015. WordPress is the most popular blogging system in use on the Web, at more than 60 million websites.
WordPress has a web template system using a template processor.
WordPress users may install and switch between themes. Themes allow users to change the look and functionality of a WordPress website or installation without altering the information content or structure of the site. Themes may be installed using the WordPress “Appearance” administration tool or theme folders may be uploaded via FTP. The PHP, HTML (HyperText Markup Language) and CSS (Cascading Style Sheets) code found in themes can be added to or edited for providing advanced features. Thousands of WordPress themes exist, some free, and some paid for templates. WordPress users may also create and develop their own custom themes if they have the knowledge and skill to do so.
WordPress’s plugin architecture allows users to extend its features. WordPress has over 30,000 plugins available, 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 displaying features, such as the addition of widgets and navigation bars. But 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.
Native applications exist for WebOS, Android, iOS (iPhone, iPod Touch, iPad), Windows Phone, and BlackBerry. These applications, designed by Automattic, allow a limited set of options, which include adding new blog posts and pages, commenting, moderating comments, replying to comments in addition to the ability to view the stats.
WordPress also features integrated link management; a search engine–friendly, clean permalink structure; the ability to assign multiple categories to articles; and support for tagging of posts and articles. Automatic filters are also included, providing standardized formatting and styling of text in articles (for example, converting regular quotes to smart quotes). WordPress also supports the Trackback and Pingback standards for displaying links to other sites that have themselves linked to a post or an article.
Multi-user and multi-blogging
Prior to version 3, WordPress supported one blog per installation, although multiple concurrent copies may be run from different directories if configured to use separate database tables. WordPress Multisites (previously referred to as WordPress Multi-User, WordPress MU, or WPMU) was a fork of WordPress created to allow multiple blogs to exist within one installation but is able to be administered by a centralized maintainer. WordPress MU makes it possible for those with websites to host their own blogging communities, as well as control and moderate all the blogs from a single dashboard. WordPress MS adds eight new data tables for each blog.
Source: Dinesh Ghimire