A child theme is a theme that uses the core “parent” theme files, unless one of those files (in the root directory of the parent theme) are copied and added to the child theme.
In that case, the copied file is used on your website so you can make changes to it without touching the parent theme.
This is useful as when updates are released for the parent theme, WordPress deletes the directory and uploads the new one. Any changes you made to the parent theme files are discarded and replaced with the newly updated files.
Better with food, tables and music
A child theme is a theme that uses the core “parent” theme files, unless one of those files (in the root directory of the parent theme) are copied and added to the child theme. In that case, the copied file is used on your website so you can make changes to it without touching the parent theme.
This is useful as when updates are released for the parent theme, WordPress deletes the directory and uploads the new one. Any changes you made to the parent theme files are discarded and replaced with the newly updated files.