WCAG: The Technical Standard for Web Accessibility
WCAG is the technical rulebook for making web content usable by people with disabilities. It provides testable criteria for websites and apps, often required by law. The footgun is aiming too low; Level AA is the standard target, not just Level A.
Why it exists
The web was built without a universal plan for accessibility, leading to a digital world that excluded many people with disabilities. WCAG was created to provide a single, shared, international standard to fix this, ensuring content is usable by everyone, regardless of their abilities.
The mental model
Think of WCAG not as a set of best practices, but as a building code for the web. Just as a building must have ramps and accessible restrooms to be legally compliant and usable by all, a website or app must meet specific, testable criteria to be considered accessible. It's about conformance to a technical standard, not just good intentions.
How it works
WCAG is structured hierarchically. At the top are four core principles: Perceivable, Operable, Understandable, and Robust (POUR). Under these principles are guidelines, which are general goals. The most important part for developers are the testable "Success Criteria" under each guideline. These criteria are what you actually test against. Each success criterion is assigned a conformance level: A (lowest), AA (mid-range), or AAA (highest). To "meet WCAG," your content must satisfy all success criteria at a given level, typically Level AA.
When to use it
Use WCAG as the definitive checklist when building or auditing any digital product, including websites, native mobile apps, and internal software. It's essential when your organization is legally required to be accessible (common for government, education, and many large businesses) or when you want to ensure the broadest possible audience can use your product. It is the technical foundation for accessibility policies worldwide.
When not to use it
WCAG is not an introductory tutorial on accessibility. If you're completely new to the topic, start with more foundational resources like the WAI's "Accessibility Fundamentals" first. WCAG tells you what to do, not how to do it or why it matters in a narrative sense. It's a standard for evaluation, not a beginner's guide.
One canonical example
A common WCAG success criterion is 1.4.3 Contrast (Minimum), which is at Level AA. It states that the visual presentation of text must have a contrast ratio of at least 4.5:1 against its background. This is a specific, measurable, and testable rule. A developer can use a tool to check if their gray text on a light gray background passes this ratio. If it's 4.4:1, it fails. If it's 4.5:1, it passes. This removes ambiguity from design and implementation.
Interview question
What is the primary distinction between WCAG and general web accessibility best practices?
- a.WCAG focuses exclusively on visual design elements like color contrast ratios.
- b.WCAG defines specific, testable success criteria with required conformance levels.Correct
- c.WCAG offers optional recommendations that are rarely legally binding.
- d.WCAG provides narrative explanations and beginner tutorials on accessibility.
Why? this is the answer
WCAG is described as a "building code" with "specific, testable criteria" and defined conformance levels (A, AA, AAA), making it a technical standard. Option D is incorrect because the card states WCAG is not an introductory tutorial.
Just read this? Test yourself on what you have been reading.
Read the original → w3.org
You just looked this up. Could you explain it out loud?
That is the part interviews actually test. Tezvyn takes questions like this one and gives you what the interviewer is really checking, the answer that lands, and the mistake that ends the conversation, in the four minutes before your next meeting.
The iPhone app is on the way
We are building it. Until it lands, nothing here is held back from you: every interview card, your saved cards, streaks and the job board all work in Safari, plus hundreds of free practice quizzes of thirty questions each. Sign in and it all carries over to the app the day it arrives.
Want it as an icon? Tap Share at the bottom of Safari, then Add to Home Screen. It opens full screen and the cards you have read stay available offline.
We are hiring for this. Open roles that interview on accessibility — each one lists the topics its interview covers.
See open roles