Most users think it’s simple, because they type a URL and a page loads quickly, but a lot goes on behind the scenes.
Our guide will explain how WordPress work behind the scenes, as well as give you a handy infographic you can follow along with.
Table of Contents
What is WordPress?
The WordPress content management system and website builder allows you to create and manage websites. The software is free and can be used by anyone to make any kind of website.
In 2003, it was a blogging platform, but soon developed into a CMS and then into a full-fledged website builder. There are more than 38% of websites on the Internet that are powered by WordPress today.
You can learn more about WordPress work behind the scenes, evolution, history, pros & cons by reading our guide What is WordPress? How much does WordPress cost?
Why You Should Learn How WordPress work behind the scenes?
Anyone can study the code of WordPress and write custom apps (plugins) and templates (themes) for it since it is open source.
The more you know about how WordPress work and WordPress work behind the scenes, the more you will be able to do with it. Improve the performance of WordPress and write better code for your own projects with these tips.
Step-by-step instructions will guide you through the whole process. As soon as a user requests a page, we will begin tracking until that page is fully loaded.
Ready? Let’s get started.
For more details, please see our written tutorial below.
1. Load wp-config.php File
In WordPress, the wp-config.php file is the configuration file. Your WordPress database information is contained in this file, as well as global variables for your WordPress site. Due to its obvious purpose, this file is the first one WordPress loads. The wp-config.php file and how to edit it are explained here.
2. Setup Default Constants
WordPress will move on to setting default constants after loading the wp-config.php file. It includes information like the default WordPress upload location, maximum file sizes, and other default constants.
3. Load advanced-cache.php File
WordPress will load advanced-cache.php if it exists on your site. Several popular WordPress caching plugins use this file as a drop-in file. Your site’s plugins screen will display a new item called Drop-ins if this file is used.
4. Load wp-content/db.php File
The db.php file inside the wp-content folder allows developers to create their own database abstraction layers. WordPress caching plugins commonly use it to improve database performance. WordPress will load this file if it is present on your website.
5. Connect MySQL and Select Database
It is now possible for WordPress to proceed further based on the information it has. After connecting to the MySQL server, the database will be selected.
WordPress will quit if it cannot establish a database connection and you will see the “Error establishing database connection” error.
It will move on to the next step if everything goes well.
6. Load object-cache.php or wp-includes/cache.php File
In this case, WordPress will look for the file object-cache.php. A PHP file called wp-includes/cache.php will be loaded in the case that the file does not exist.
7. Load wp-content/sunrise.php File
The sunrise.php file will now be checked in the wp-content folder if it exists in a multisite network.
8. Load Localization Library
The l10n.php library will now be loaded in the wp-includes folder. It loads the localization system for WordPress, loads translations, sets locales, etc. Learn how to use WordPress in other languages in our guide.
9. Load Multisite Plugins
WordPress will now load the multisite plugins if the network is multisite. Find out how plugins work on a WordPress multisite network.
10. Do Action ‘muplugins_loaded’
It is now WordPress that runs muplugins_loaded. On a WordPress multisite, this action is available only to network activated plugins.
11. Load Active Plugins
All active plugins on the site will now be loaded by WordPress. This is done by checking the active_plugins entry in the options table of your WordPress database. Installed but unactivated plugins are ignored by WordPress.
12. Load pluggable.php File
A WordPress plugin can redefine functions in the pluggable.php file. In this case, WordPress will check if another plugin has already defined the functions contained in this file. If not, it will define them on its own.
13. Do Action ‘plugins_loaded’
Plugins will now be loaded by WordPress through the action ‘plugins_loaded’. Developers can hook their functions after all active plugins are loaded so they can run after all active plugins are loaded.
14. Load Rewrite Rules
The rewrite rules will now be loaded by WordPress. WordPress uses SEO-friendly URLs with these rewrite rules.
15. Instantiate $wp_query, $wp_rewrite, $wp
The following objects are loaded at this point:
$wp_query: WP_Query class is held in this global instance. In a typical WordPress query format, it tells WordPress what content is requested.
$wp_rewrite: Your WP_Rewrite class is stored in this global instance. WordPress uses your rewrite rules and functions to determine which URL to use to display the requested content.
$wp: An instance of the WP class containing functions to parse your request and execute the main query.
16. Do Action ‘setup_theme’
Now WordPress will run the action ‘setup_theme’. WordPress loads your theme before this action runs.
17. Load Child Theme’s functions.php File
WordPress themes use the functions.php file to add theme-specific features to their websites. The functions.php file of your child theme will now be loaded if you are using a child theme.
Otherwise, it will load the functions.php file for your current active theme.
18. Load Parent Theme’s functions.php File
The functions.php file of your parent theme will now be loaded if you are using a child theme.
19. Do Action ‘after_setup_theme’
The theme functions are loaded after WordPress has configured the theme. The first action a theme can perform.
20. Setup Current User Object
A user object is loaded at this point by WordPress. WordPress can manage requests based on the role and capabilities of the user.
21. Do Action ‘init’
The crucial information needed by WordPress work behind the scenes has been loaded so far. The ‘init’ action is now fired.
WordPress can execute code after all previously mentioned information has been loaded by this action.
22. Do Action ‘widget_init’
With widget_init, developers can register widgets and run code they need at this moment.
23. Run wp()
It now calls the wp() function in wp-includes/functions.php. It then calls $wp->main to set up the WordPress query globals $wp, $wp_query, and $wp_the_query.
24. Parse Request
WordPress has now obtained all of the information it needs to parse a user request. Initially, it checks whether the rewrite rules match the user’s request.
After that, it runs query variable filters, requests action hooks, and sends header requests.
25. Run Query
WordPress will set the is_404 variable if there is no content matching the query.
WordPress will then load query variables if this is not the case.
Then it will run WP_Query->get_posts().
Using the WP_Query object, it fires DO_ACTION_REF_ARRAY ‘pre_get_posts’ action.
In order to clean up the query and run some final checks, WordPress will run apply_filters.
Posts are now fetched from the database and the_results and the_posts filters are applied.
WordPress returns the posts at the end of the query part.
26. Do Action ‘template_redirect’
The template_redirect action will now be run by WordPress. Just before WordPress determines which template page to load, this hook runs.
27. Load Feed Template
RSS feed templates are loaded when WordPress receives a feed request.
28. Load Template
It will now look for the template file based on the WordPress template hierarchy. The template is then loaded, which usually includes a WordPress loop.
29. Do Action ‘shutdown’
WordPress fires the shutdown action just before it ends all PHP execution.
There is a problem with WordPress here. The code has been run and the web page requested by the user has been generated.
Your web hosting server now responds to a user’s request by sending them the WordPress-generated web page. A user’s browser displays this page using HTML, CSS, and Javascript code.
It’s amazing, isn’t it? All of these things happen within milliseconds. The best WordPress hosting services will load your page within a couple of seconds if you are using one of them.
It is our hope that this article has helped you understand how WordPress work behind the scenes. We also have a step-by-step guide for beginners on how to boost WordPress work behind the scenes, speed, and performance.
Managing Director affiliated with Perfect Web Solutions. In the early years of the company, I was responsible for restructuring Perfect Web Solutions's business model into that of an IT company.
My team has been working very closely with Perfect Web Solutions for about 6 months now and they have been great to work with! They are very quick with any feedback we provide them and they have created a wonderful and powerful website for us. I would definitely recommend them!.
