4 minute read

The four principles of WCAG

Before we dive into the details, let’s talk about the foundation of WCAG: four principles that everything else is built on.

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They might sound a bit abstract at first, but don’t worry—we’ll keep it simple and relatable.

These principles are less about rules and more about perspective. They’re here to help you think about accessibility in a way that works for everyone. Don’t worry if it takes time to connect the dots—that’s what the rest of this guide is for.

1. Perceivable

Think of Perceivable as making sure everyone can sense your content, whether through sight, sound, or touch. It’s about presenting information in ways that everyone can experience—whatever tools they’re using.

Ever tried to watch a video on mute and couldn’t follow along without captions? Or maybe you’ve squinted at light gray text on a white background? Those are examples of barriers to perceivability.

Perceivable design means:

  • Adding captions to videos so they’re understandable even without sound.
  • Using alt text for images, so screen readers can describe what’s there.
  • Choosing text and background colors that make content easy to read.

It’s all about making sure that no matter how someone interacts with your site—visually, audibly, or using assistive tech like a screen reader—they get the full picture.

2. Operable

Operable is about making sure people can use your site—whether they’re clicking, tapping, typing, or talking. It’s not just about having features; it’s about making them usable for everyone.

Ever tried to click on a tiny button on your phone and missed? Or struggled to pause a slideshow that was moving too fast? These are operability issues that can make a site frustrating—or even impossible—for some people to use.

Operable design means:

  • Making buttons and links big enough to tap easily.
  • Letting users navigate with a keyboard or voice commands, not just a mouse.
  • Giving control to the user—like being able to stop or pause moving content.

It’s about removing barriers so everyone can interact with your site in a way that works for them.

3. Understandable

Understandable is about making your site and its content easy to follow. It’s like giving someone clear directions—they should know what to expect and how to move forward.

Ever run into a wall of technical jargon or acronyms you didn’t recognize, leaving you unsure what to do next? Or seen an error message so vague it might as well have said, “Something went wrong”? When things aren’t understandable, users can feel stuck and frustrated.

Understandable design means:

  • Using clear and simple language.
  • Keeping navigation predictable—so links, buttons, and menus work the way people expect.
  • Giving helpful feedback when users make mistakes, like telling them what’s wrong with a form entry.

It’s about making things intuitive and avoiding those “Wait, what just happened?” moments.

4. Robust

Technology changes fast. New devices, browsers, and tools come out all the time, and Robust is about making sure your site can keep up—no matter how people are accessing it.

Ever opened a site on your phone, and everything was squished or overlapping? Or tried to use a screen reader, only for it to announce “button, button” without telling you what the button does?  Those are examples of a lack of robustness.

Robust design means:

  • Using clean, consistent code that’s easy for browsers and assistive tech to understand.
  • Testing your site with different tools, like screen readers or voice navigation.
  • Future-proofing your site so it works with new technologies as they evolve.

It’s like building a website with a solid foundation—it’s not just about working today; it’s about staying reliable and usable tomorrow, too.

Why POUR Matters

These principles are less about rules and more about perspective. They’re here to help you think about accessibility in a way that works for everyone. Don’t worry if it takes time to connect the dots—that’s what the rest of this guide is for.

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