core

Theme

A collection of template files that control the visual appearance and layout of a WordPress site. Themes determine how content is displayed to visitors.

Themes are the design layer of WordPress. While plugins add functionality, themes control how your site looks and how content is structured for visitors.

Theme Structure

A WordPress theme consists of template files (PHP), stylesheets (CSS), and optionally JavaScript files. At minimum, a theme requires a style.css file with a theme header and an index.php template.

Classic vs Block Themes

WordPress supports two theme architectures:

  • Classic themes use PHP template files like header.php, footer.php, and single.php to render pages.
  • Block themes use HTML template files and the Site Editor for full visual customization without code.

Block themes are the modern standard and support Full Site Editing (FSE).

Child Themes

A child theme inherits the functionality and styling of a parent theme while letting you make customizations that survive parent theme updates. Always use a child theme when modifying a third-party theme.

Choosing a Theme

Consider these factors when selecting a theme:

  • Performance (lightweight code, minimal dependencies)
  • Compatibility with popular plugins
  • Responsive design for mobile devices
  • Regular updates and active support
  • Accessibility compliance
  • Astra — Lightweight and highly customizable
  • GeneratePress — Performance-focused with clean code
  • Kadence — Modern block theme with a free starter templates library
  • Twenty Twenty-Five — The default WordPress block theme
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