When you are working with your theme’s code, if you make changes to the theme’s files that will overwrite your original theme file and you cannot go back to the old theme. so to avoid an issue you must create a child theme before start working with your website theme. A WordPress child theme is a theme that inherits the all functionality of parent (original) theme. Child theme allows you to add, edit, and delete the functionality of the original theme. And it will not affect your original theme.
That means before the theme editing, creating a child theme is very important because when you are working with your theme’s code you may made mistakes in changing codes, and it will affect your original theme. And you will never get back your theme back. In case of paid theme you will drop your money. If it is free theme, it’s ok; you can download another one and start working. But there also you will lose your valuable time. Child themes help you to make changes without affecting the original theme’s code. So before working with your theme create a child theme and make separate files for it. It will help you easy to customize your theme without affecting your original theme. So creating a child theme is the safest way to modify your existing theme. A child theme is required only one file that is “style.css”. All other files are optional.