Short answer
WordPress is an open-source content management system (CMS) for publishing and managing websites. It runs on PHP, a MySQL/MariaDB database, and uses a themes and plugins system for presentation and extendable functionality. The software is distinct from the WordPress.com hosting service.
What you get, and what you still need
WordPress, by default, provides an editor, media management, user accounts and a system for publishing pages and posts. A theme controls much of the visual. Plugins add capabilities such as forms, search tools or WooCommerce shopping features.
You still need hosting, a domain and someone responsible for updates. A managed host may handle parts of that work. “Managed” is not a universal list of included services.
WordPress.org describes the project and its open-source licence. Its hosting requirements explain the PHP, database and HTTPS dependencies. Minimum compatibility is not a recommendation to run an obsolete PHP version.
Why the market-share headline needs a label
WordPress.org describes WordPress as powering over 43% of websites on its About page, checked October 21, 2026. Treat this as a dated, attributed estimate, not a permanent constant. CMS market share and share of all websites have different denominators.
The useful conclusion is not that popularity makes WordPress the right choice for everything. It is that its ecosystem is large enough to matter: existing sites, trained editors, a wide plugins library, agencies and integrations all create reasons to keep using it.
When it fits
WordPress is worth considering when a team needs familiar publishing tools and an existing ecosystem. A highly specific application may need a different foundation. A simple site may need less software.
For an existing site, ask what its editors need, which plugins are essential and who owns maintenance. Replacing a working CMS is a project, not a security patch.