If you are planning to start with WordPress and are about to build your first website with it then this article might be a useful heads up for you. WordPress is really great, you can build all sorts of websites with it and I can’t recommend it enough. However starting off on the wrong foot leads to disappointment and might chase you away for good. So read on.
Bad experience due to knowledge gap
It’s not uncommon that people who have a bad experience with certain software instantly blame the software instead of themselves. Often these kind of mistakes are a result of lacking knowledge about how to work with the software sometimes combined with a fair amount of self overestimation. We all remember that ‘uncle’ helping you speeding up your Windows PC, deleting essential system files and leaving your computer in a total mess, right?
Often mistakes that are discussed on the WordPress forums and in articles are about the usage of outdated, nulled and bloated themes and plugins. However what is not that commonly discussed, but what is also important:
Never ever edit or delete the core files of WordPress!
What are WordPress core files?
The WordPress core files are the PHP files that contain the main functionality of WordPress [source: WPengine]. These files should never be modified unless you are planning to fork WordPress. If you don’t know what a fork is, then simply don’t touch these files.
Where the WordPress core files are located
The image below shows an overview of the WordPress core files. Basically it’s every WordPress file except the wp-config.php file and everything inside the wp-content folder.

Why you shouldn’t change the core files
1. It may break your site
If you don’t know what you are doing, modifying the core files can lead to your website becoming inaccessible. Imagine trying to fix your website after something like this happens and everything you can do is guessing your way around and googling. Doesn’t sound great huh?
2. Security issues
Another important reason to never touch the WordPress core files is that it breaks the overall website security. Especially (but not limited to) if you are inexperienced to WordPress, even if you know PHP. When you get hacked you might blame WordPress, but if you modified the core, then you should blame yourself. One very self confident person never out-rules a team of experienced people that are building WordPress 24/7.
About the GPL license and forking
WordPress gained popularity since the early days because of their mission to democratize publishing; Everyone should be able to run a blog or website. The famous 5 minute installation process, the GPL software licensing and the WordPress community made WordPress the most popular CMS is the world. The GPL license provides four core freedoms:
The 1st Freedom
To run the program for any purpose.
The 2nd Freedom
To study how the program works and change it to make it do what you wish.
The 3rd Freedom
To redistribute.
The 4th Freedom
To distribute copies of your modified versions to others.
[source: wordpress.org]
With WordPress gaining more popularity, many types of users and developers became part of the WordPress ecosystem. All having a different kind of skill level and different learning methods.
Here’s where it can get confusing
The 2nd freedom of the GPL is amazing for software developers because they have the freedom to fork the software entirely. But it also can lead to confusion for beginners.
When an average user or ‘do it yourself’ developer starts muddling in the WordPress core files but at the same time expects the software to run smoothly, this is where the bad experience comes in.
In short
So basically, if you are are starting with WordPress and want to benefit from the security, support and updates, then stay of the core files. If you want to use it as a starting point to build your own type of CMS then fork it.