Discovering what a child theme is

Working as a PrestaShop developer, you are likely to get some customers requesting things such as customizing an FO template structure, changing colors, CSS styles, or JavaScript scripts.

Some of your customers will have PrestaShop websites already working with an existing theme. Even if it would be quicker to locate the code responsible for what we need to change in the original theme and make our modifications to get the requested result, it is not recommended to change anything directly in a theme that is not ours.

First, it is dangerous to change something in an existing theme as, sometimes, it is not well backed up. Then, we don't really know the impact on a template or an asset change in terms of dependencies. Moreover, if our customer comes back to us by requesting to install the latest updates of their original theme, it will completely erase our previous changes. We will need to check all the modified files to merge our work with...