What is a parent theme?
A parent theme in WordPress is any theme that is available on a marketplate, from a vendor or downloaded from WordPress.org.
When you are starting with a fresh WordPress install, it is comes with a few themes preinstalled. They are named by the year they are released, Twenty Seventeen theme was released in 2017 for example.
What is a child theme in WordPress?
A child theme is a theme that is a similar version of the parent. The files pull information from the parent theme, but adds adds security if the parent theme is ever updated.
Why is a Child Theme Important?
If you make changes to a theme without using a child theme and the main or parent theme is updated, you can loose the styling and work that you have done to your site.
That is why it is best practice to use a child theme. I’ve been in the situation where the main theme had to be updated and and I didn’t use a child theme.
I made rookie mistake when I first started. I didn’t have a child theme and lost all of my customizations.