A Joomla child template inherits files from a parent template while keeping local changes separately. The selected parent must support the mechanism.
How inheritance works
When a required file is absent from the child, Joomla uses the parent’s file. Changed files and assets are placed in the child using the supported structure. This differs from copying a template style, which changes parameters without creating a separate file set.
Updates and dependencies
Updating the parent normally leaves the Joomla child template’s own files intact. Changes to parent layouts and interfaces can still require adjustments in the child. The parent remains a dependency and should not be removed arbitrarily.
A Joomla child template helps maintain presentation changes. After updates, test pages, assets, overrides and parent compatibility.