What is Child Theme in WordPress?
The concept of WordPress Child Theme is similar to human child that basically contains all the characteristics of your WordPress Parent Theme. Millions of WordPress developer is Working to create beautiful design WordPress themes, but the customer demand is always different.
If you are a WordPress user and you have good knowledge on coding, you can easily update the theme by adding codes on it. But it will be erased when theme developer bring new update on there theme. If you click on the update button, it will remove all of your previous changes.
To keep your self-modifications you have to activate the Child Theme & add codes on it. This way your codes with not be affected when theme update happens. Because, the parent theme will adopt the updates & you are using the child version.
How to Create Child Theme?
Simply copy your theme folder and rename it as child-ThemeName. Then edit the style.css file & declare the theme name as Child ThemeName. Once you complete theme steps, you have to activate your child theme from the WordPress appearance section.
Most of the theme developers provide child theme along with the parent theme. It's a good practice & nowadays all the popular WordPress Marketplaces make it mandatory to attach child themes.