WordPress Themes – All You Need to Know

WordPress Themes – What Are They?

A WordPress theme is a collection of files, largely consisting of templates (written in PHP), Cascading Stylesheets (CSS), graphics and photos, JavaScript and texts. Together they determine the design and layout of your website. In layman terms, themes control the design and layout of your website. To change the look of your WordPress site, simply install and activate a new theme.

How Do Themes Work?

In a WordPress website, content data is stored in their raw form in the database. Each time a visitor’s browser sends a request for a page on your site, the theme, through it’s php template file, pulls out the required data to form that page and runs it through the CSS to style it, so that it displays as intended on the browser.

How Do Themes and Templates Differ?

In the WordPress world, when we refer to themes, we refer to the full collection of files (i.e. templates, CSS, images, JavaScript, text and all). Collectively, they determine how your website looks. So templates are just one type of file, found within a complete theme. Each template controls only a part of a page and not the whole website. More importantly, templates cannot work on their own; they may be able to pull out data to form a page, but this data will be in their raw, un-styled form.

Difference Between Themes and Plugins

In the WordPress ecosystem, plugins are meant to add functions and features to your website, over and above what is provided by the WordPress core, while themes control the design. There are themes that come bundled with needed functionalities as well but the best practice, recommended by WordPress.org is to let plugins, rather than themes provide all essential functions. This is so that site owners will have the option of changing site design from time to time (by changing themes) without losing all the needed functions.

How To Choose A Theme?

Choose a Design You Like

There are 2 ways to do this:
1. Check out the theme demos on the developer’s website; or
2. Browse the internet looking for sites you like.

Of the 2 methods above, I generally prefer the latter. But when browsing other people’s websites, avoid looking at those of your direct competitors; you don’t want your site looking similar to theirs. Instead look at sites belonging to businesses within the same industry but in different countries. If you find a site you like, check if it’s a WordPress site. If it’s not, move on. If it is, check if it’s a theme you can get your hands on. Some themes are customized or proprietary and as such, not available for sale. These are usually websites belonging to large MNCs. To find templated websites, try looking at those belonging to smaller players within your niche.

To check if a site is build on WordPress plus the theme it is using, simply visit https://whatwpthemeisthat.com and perform a search there. If it’s a WordPress site with a publicly available theme, the tool will show you where to buy that theme. But don’t rush into buying it just yet; there are 4 more important checks you have to perform, namely, to check:

1. If the theme is mobile responsive
2. The speed at which it loads
3. Compatibility with all major browsers
4. How frequently the theme is updated

Mobile Responsiveness

Given that mobile traffic constitute about 50 % of all web traffic, its important that your site is mobile responsive. And because mobile responsiveness is a design feature, it is control by themes. Choose a mobile responsive theme and your website automatically becames mobile responsive and friendly.

By far the easiest way to check if a theme is mobile responsive is to resize your browser and check if the website content adjusts and adapts to the different browser screen sizes. If so, the theme is deemed mobile responsive and will be able to display the website correctly for all different screen sizes.


Loading speed, to an extend is affected by themes. A poorly developed theme, with bloated codes will slow down the loading speed of a website. Slow loading websites usually results in higher bounce rates which in turn can impact your web conversions and profits negatively. Page experience, as measured by the core web vital scores, will be bad as well and this in turn may affect your Google organic rankings, come May 2021.

For speed, we usually do an initial eyeball test i.e. we click through some of the internal links on the website to see how fast these pages load. If it’s slow, we won’t recommend the theme. If it passes our eyeball test, we will test the site using the PageSpeed Insights tool Google provides to how it does in terms of Core Web Vitals for mobile. Why mobile only? Because that’s the score used by Google in their Page Experience update scheduled for May 2021. Plus if a site does well on mobile, performance over desktop will usually not be a problem.

Compatibility With Different Browsers

Just because a theme displays correctly on one browser does not mean it will automatically display correctly on others. That’s why we check all websites we build to see how they look on all the major browsers e.g. Chrome, Safari and Firefox. And while you are at it, don’t forget to check the same on mobile as well.

Update Frequency

The WordPress CMS is actively maintained with updates being issued very frequently. As WordPress updates, they may add new functions and retire others. If your theme is using a function that WordPress has retired in its current update, your website may crash. That’s why as WordPress updates, it’s important that theme developers likewise update their themes to ensure compatibility. A theme that has not been updated for 2 years or more has likely been abandoned by the developer and no matter how much you like it, it’s best not to use.

Compatibility with WordPress aside, it’s through theme updates that developers fix bugs on their themes, issue security patches if vulnerabilities are found and/or provide feature enhancements. That’s why it’s so important that the theme you buy must be actively maintained.

The easiest way to check the frequency of updates, is to check the theme’s changelog. Most reputable developers will log all their updates in a changelog, publicly accessible by everyone. All you have to do is Google for it.

Other Considerations

Free Vs Paid Themes

While there are many free themes available, my preference has always been for paid themes. Why? Because, from experience, many of the free themes have already been abandoned by their developers or will be abandoned somewhere down the road in future. Popular premium themes from reputable developers are less likely to be abandoned in the conceivable future.

eCommerce Websites

If you intend to use the theme to build an eCommerce website, it’s best to take a look at how the theme displays your store, individual product, cart, check-out and my account pages to see if you like them. Without knowing coding, you will not be able to change the design of these pages, so it’s best you make sure you like them before buying.

Most theme developers have a page where they demo their theme. Just visit that page and you will be able to check.

Final Thoughts

Themes control the design of your website. When a theme fails to work as intended, the display errors can be very visible. Poorly coded themes as well as those not actively maintained can slow the loading speed of your website or contain security holes. As such it is important you follow the tips on this post and choose a good theme.

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I'm a web design and SEO trainer in Singapore. To date, I've trained more than 5,000 people in SEO and WordPress web design. I love reading stuff related to digital marketing and especially enjoy public speaking. Prior to becoming an entrepreneur, I worked 18 years in the life insurance industry - 4 years in HSBC Insurance as the Chief Agency Officer and another 14 years in AIA, with my last role there being that of Regional Director of Agencies.

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