A WordPress child theme is a child theme that inherits the features and styling of the main (parent) theme used on a WordPress website, but allows for customizations without replacing it. A child theme allows the user to add custom CSS codes, function changes, or additional design elements while maintaining the functionality and design of the parent theme.

The biggest advantage of using a child theme is that customizations can be preserved without being affected by updates to the parent theme. This allows you to keep your theme up to date without losing your customizations. A child theme also makes the customization process more organized and manageable because changes are made to the child theme, not directly to the parent theme.