Web accessibility ensures everyone, including people with disabilities, can perceive, understand, navigate, and interact with websites, based on four core WCAG principles: 1. Perceivable—provide text alternatives, captions, sufficient contrast, and resizable content; avoid light gray on white. 2. Operable—ensure keyboard navigation, enough time to read, no flashing elements, visible focus indicators; test with Tab key. 3. Understandable—use clear language, consistent interactions, error handling, and visible labels; avoid vague error messages. 4. Robust—use semantic HTML, follow standards, test with screen readers; avoid fake buttons made from divs. These principles benefit all users and improve overall usability when implemented correctly.

Web accessibility isn’t just a nice-to-have—it’s about making sure everyone, including people with disabilities, can perceive, understand, navigate, and interact with your website. The core principles are outlined in the WCAG (Web Content Accessibility Guidelines), and they’re broken down into four main categories: Perceivable, Operable, Understandable, and Robust, or POUR for short.

Let’s break them down one by one in a way that makes sense for real-world use.

1. Perceivable – Information and interface components must be presentable to all users

This means content should be easy to sense, no matter how someone is accessing it—whether through sight, sound, or touch.

• Provide text alternatives for non-text content like images, icons, and videos. Screen readers can't interpret visual-only elements without proper alt text.
• Make sure multimedia has captions or transcripts so users who can't hear can still follow along.
• Use sufficient color contrast. Don’t rely on color alone to convey meaning—for example, don’t just mark required form fields in red; add an asterisk or label too.
• Ensure content can be resized without breaking layout. Users with low vision often zoom in, so make sure your site handles that gracefully.

One common mistake? Using light gray text on a white background. It might look clean, but it fails basic contrast checks and makes reading harder than it needs to be.

2. Operable – UI and navigation must be functional for all users

Even if someone can see the content, they need to be able to interact with it using different tools—like a keyboard, screen reader, or voice command software.

• All functionality should be available from a keyboard. Some users can’t use a mouse, so tabbing through links, buttons, and menus should work smoothly.
• Give users enough time to read and use content. Auto-advancing slideshows or disappearing alerts can frustrate users who take longer to process information.
• Avoid flashing or blinking content. Anything that flashes more than three times per second can trigger seizures.
• Make sure focus indicators are visible. When you tab through a page, the focused element should clearly show where you are.

A good test: Try navigating your own site using only the Tab key. If it's confusing or skips around, there's room for improvement.

3. Understandable – Content and interface must be clear and predictable

Users should be able to understand both the language and the interaction patterns on your site.

• Use clear and simple language, especially when explaining processes or instructions.
• Make sure interactive elements behave consistently. For example, if clicking a button opens a modal, don’t have another button labeled the same that does something completely different.
• Help users avoid and correct mistakes. If someone fills out a form wrong, give specific error messages and let them fix it easily.
• Labels and instructions should be clear. In forms, placeholder text isn’t enough—use visible labels so screen readers and users alike know what each field is for.

An example of this going wrong: a form that says "Error" without pointing out which field is wrong. That just leaves users guessing.

4. Robust – Content must work across current and future technologies

This principle ensures that your website remains accessible as technology evolves and is compatible with assistive tools like screen readers.

• Use semantic HTML properly. Things like <button></button>, <nav></nav>, and <header></header> aren’t just for developers—they help screen readers understand structure and function.
• Keep up with standards. Avoid outdated practices or unsupported features that may not work well with newer devices or assistive tech.
• Test with screen readers and tools regularly. What looks fine visually might not be readable by assistive software if the code isn’t structured right.

For example, using a

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