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The importance of creating a child theme when customising WordPress

Alejandro Frades
La importancia de crear un tema hijo al personalizar WordPress Modular

Digital marketing agencies are constantly looking for ways to optimise the creation and management of websites for their clients. WordPress, because of its flexibility and wide adoption, presents itself as an ideal solution. The use of child themes stands out as an essential strategy for customising and keeping websites up to date without compromising the original design or functionality. This guide is designed to provide marketing agencies with the information they need to make the most of child themes in WordPress, from their basic concept to their effective implementation.

What is a child theme in WordPress?

A child theme in WordPress is essentially a sub-theme that inherits all the features, functionality and styles of a pre-existing theme, known as a parent theme. This inheritance relationship allows digital marketing agencies and developers to apply specific and extensive customisations without modifying the original code of the parent theme. The structure of a child theme is ideal for projects that seek adaptability and customisation, while maintaining the integrity of the website’s core design and functionality.

Using child themes makes it easy to update the parent theme without losing the customisations made, a significant advantage for maintaining the security and compatibility of the website over the long term. In addition, working with child themes simplifies the design and development process by allowing agencies to focus on specific modifications without the need to rework or adjust the code base each time the parent theme is updated.

Differences between child theme and parent theme

The main difference between a child theme and a parent theme lies in their function and use within WordPress:

  • Parent Theme: It is the main theme from which the features and design are inherited. It functions as the foundation upon which child themes are built. By updating a parent theme, aspects such as security, functionality and compatibility with the latest versions of WordPress are improved, without affecting the customisations made in the child themes.
  • Child Theme: It is created specifically to make customisations and changes to the design or functionality of the website, without directly altering the code of the parent theme. This allows for greater flexibility and security in web development, as any adjustments or updates to the parent theme do not overwrite the customisations made in the child theme.

Why should a marketing agency doing development work always use a child theme?

For digital marketing agencies, always having a child theme on WordPress projects is not just a recommendation; it’s an essential strategy that offers multiple benefits in both the short and long term. Here are the main reasons why agencies should adopt this practice:

1. Advanced Customisation without Limitations

Child themes allow deep and detailed customisation of websites, enabling agencies to implement unique designs and client-specific functionality without altering the code of the parent theme. This unrestricted customisation capability ensures that agencies can meet the exact expectations and requirements of their clients, offering truly bespoke solutions.

2. Secure Maintenance and Updates

Updating a WordPress theme is crucial for the security and performance of the website, but it can also be a source of stress if there are direct customisations to the theme. By using a child theme, agencies can apply updates to the parent theme without fear of losing custom work, ensuring that the website remains secure and functional with the latest security enhancements and fixes.

3. Operational Efficiency and Time Savings

By establishing a workflow that includes the creation of child themes, agencies can reuse customised solutions for different clients, significantly reducing development time. This approach not only improves operational efficiency but also allows agencies to focus on more strategic aspects of the project, such as SEO, user experience and conversion optimisation.

4. Independence and Flexibility

Child themes offer agencies the flexibility to experiment and test new features or design changes without affecting the stability of the website. This independence is crucial to the creative and technical process, allowing for quick iterations and risk-free implementation of continuous improvements.

5. Customer Investment Protection

By using child themes, digital marketing agencies protect their clients’ investment by ensuring that website-specific customisations and enhancements are not lost or require rebuilding after each update to the parent theme. This not only saves costs in the long run but also builds a relationship of trust with the client, demonstrating a commitment to the quality and durability of the delivered solution.

6. Compliance with Standards and Best Practices

Adopting child theme creation is also a sign of professionalism and technical knowledge, aligning with the best practices recommended by the WordPress community. This ensures that the solutions developed are robust, scalable and compatible with the WordPress ecosystem, facilitating integration with plugins and other tools.

How to create a child theme

Manual Creation

Manually creating a child theme is a straightforward process that offers full control over theme customisation. Here are the basic steps for creating a child theme manually:

  1. Create Child Theme Folder: The first thing is to create a new folder within the /wp-content/themes/ directory of your WordPress installation. The name of this folder must be unique and preferably related to the parent theme (e.g. temapadre-child).
  2. Create the Style Sheet (style.css): Inside the child theme folder, create a file called style.css. This file should contain the basic information for the child theme, including the theme name, description, version, and the Template tag indicating the name of the parent theme’s folder. Here’s an example of how the contents of this file might look:

Theme Name: Parent Theme Child
Theme URI:
Description: Child Theme for Parent Theme
Author: Your Name or Agency Name
Author URI:
Template: temapadre
Version: 1.0.0

3.Create functions.php file: Although not mandatory, creating a functions.php file in your child theme allows you to add or modify theme functionality. This file is run in addition to the functions.php of the parent theme. A common use is to glue the parent theme’s stylesheet together with the child theme’s stylesheets:

add_action( ‘wp_enqueue_scripts’, ‘my_child_theme_styles’ );
function my_theme_child_styles() {
wp_enqueue_style( ‘parent-theme-style’, get_template_directory_uri() . ‘/style.css’ );
wp_enqueue_style( ‘child-theme-style’, get_stylesheet_uri() );

Creating via a Plugin

For those who prefer a more automated solution or for projects with tight deadlines, there are several WordPress plugins that make it easy to create child themes. These plugins often offer a simple interface for generating a child theme, eliminating the need to manipulate files and directories manually.

Plugin Recommendation:

  • Child Theme Configurator: This is one of the most popular and comprehensive plugins for creating child themes. It offers an intuitive interface to select the parent theme and automatically generates the child theme with all the necessary files. In addition, it allows you to configure advanced features such as importing styles and customising functions.


The use of child themes in WordPress is essential for marketing agencies, facilitating advanced customisations without compromising security or the ability to update the site. This practice not only optimises the use of resources, but also ensures long-lasting, customised web solutions for each client. To complement this strategy and further enrich your understanding of web infrastructure, we recommend reading our article on how to know which CMS a website uses, an article to identify the platforms behind any website. Adopting child themes, along with a comprehensive knowledge of content management systems, reflects the agency’s commitment to quality, innovation and client satisfaction.

Frequently asked questions (FAQ)

1. Can I use multiple child themes from a single parent theme on the same website? Yes, it is technically possible to have multiple child themes derived from the same parent theme on a website, but only one can be activated and used at a time. This practice can be useful for testing different styles or functionality without altering the main child theme being used on the live site.

2. Do I need to have programming skills to create a child theme? It is not strictly necessary to have advanced programming skills to create a child theme, especially if a plugin is used to create it. However, having a basic understanding of HTML, CSS, and some PHP can be very helpful in customising and making the most of your child theme’s capabilities.

3. Do child themes affect the loading speed of my website? The use of a child theme, by itself, should not significantly affect the loading speed of your website. The efficiency in terms of speed depends more on the quality of the code of the parent theme, the customisations implemented in the child theme, and other factors such as hosting, image optimisation and plugin usage. It is crucial to follow web optimisation best practices to ensure fast loading times.

Alejandro Frades marketing specialist Modular
Alejandro Frades
Marketing Specialist
La mente detrás de los contenidos sociales de Modular. Siempre al tanto de las últimas tendencias para aprovecharlas y hacer que el mundo digital sea más ameno y entretenido.

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