Creating Your Own Themes
You can create your own themes if you’d like, but this takes some coding knowledge. You will need to be familiar with languages such as HTML, CSS, and PHP to create a new theme. This is beyond the scope of this class but we wanted to mention it here so that you were aware that it was possible.
Many designers create free themes for WordPress.org or they make extra money by creating WordPress themes and then selling them on theme sites. Themeforest.net is a good example of places you could sell a theme.
When you create your own custom themes, the sky is the limit as to what you can do with WordPress. There are specific standards and best practices on the WordPress.org site for creating your own themes so that they work well and are more secure. You must use these best practices if you are going to submit your themes to WordPress.org.
You can find the best practices and other information about WordPress theme development here.
Child Themes
Many times you may want to customize your free or premium theme. If you make changes to the theme, then any updates to that theme will overwrite your code. This can become a nightmare adding code back in anytime an update is required.
For that reason, child themes were created. A child theme is a theme that overlays another theme. The underlying theme is called the Parent theme. Any theme can have a child unless it’s already a child theme itself. In other words, you can’t have a parent with two levels of children (grandchildren). You can’t make a child theme on a child theme.
If you want to make changes to the code for your theme it’s best to create a child theme instead and make the changes to the child theme. The child theme only contains the changes you make so that you can update the parent theme without affecting your customizations.
Here are instructions on the WordPress.org website to help you start a child theme. Please let me know if you need help creating a child theme.
Deleting Themes
Any open source code you have on your site is a security risk. If a hacker, who knows what he’s doing, can see your code, then he can often find loopholes to get into and hack your site. So, the more open source code you can get rid of, the better.
Extra themes are code that’s not being used. This code in the extra theme is just another door for a hacker to get in unless its custom code that no one else has had access to anywhere else. It’s a good idea to remove any themes you aren’t using so that it closes that door and makes your site smaller.
NOTE: If your active theme is a child theme, you can NOT get rid of the parent theme. The parent theme must be present for the child theme to work correctly.
If you have made changes to the themes you are going to delete, you may want to make backups of those theme files first. You will need to keep this backup somewhere safe until you need to use it again. When you are ready to reinstall, you can either zip it up, or upload the files using an FTP client. (See Installing Themes) Let me know if you need help with backups
If your theme is not active and it’s not a parent theme to an active child theme, you can delete the theme. To do this, click on the theme image in Appearance->Themes. In the bottom right corner of the popup info box, will be a ‘Delete’ link. Clicking this link will delete the theme from your WordPress site.