When trying to make changes to a website, such as copyright information in the footer, a many people opt to edit their ‘parent’ themes directly. This creates a number of problems.
The biggest disadvantage is that any modifications made to the theme in this way will be lost once the theme is updated. As a consequence, users either won’t be able to keep their theme up to date (which is bad for security) or will find all of their customizations gone when they do.
A much better idea is to use a child theme. This allows you to make any number of changes to a website without touching any of the original theme files.
In this proposed session at WordCamp Kampala 2017, I propose we take a detailed look at what WordPress child themes are, how to create them and how to use them to customize WordPress websites — the right way.