A child theme in WordPress is a theme that inherits the design, features, and functionality of another theme, known as the parent theme. It allows you to make customizations without directly modifying the parent theme’s files.

This approach is important because any changes made directly to a parent theme will be lost when the theme is updated. By using a child theme, your custom code—such as style changes or functional tweaks—is kept in a separate set of files, allowing the parent theme to be updated safely without affecting your modifications.

Using a child theme is recommended when you want to customize the appearance or behavior of a WordPress site while preserving the ability to receive updates for security and performance improvements.