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Perceivable is the first WCAG principle: every user must be able to sense your content, even if they cannot see, hear, or read it the usual way.

If someone cannot even perceive a button or an image, nothing else matters. Perceivable is the foundation the other three principles build on.

Non-text content needs words. A text alternative lets a screen reader speak an image, so a blind user gets the same meaning you see. 🖼️

A deaf user cannot hear your video. Captions turn the spoken words into on-screen text, making sound perceivable through sight.

A transcript is the full text of audio or video. It helps deaf users, people in quiet rooms, and anyone who would rather read than listen.

People resize text, zoom, or switch to dark mode. Adaptable content keeps its meaning and order no matter how it is presented.

Use real HTML elements so structure survives. A heading stays a heading when styles drop, so a screen reader still knows it is a title.

If red means error, a color-blind user may miss it. Pair color with text or an icon so meaning is perceivable without seeing the hue.

Faint gray text on white fails low-vision eyes. Strong contrast between text and background keeps words readable for everyone.

Make it easy to tell things apart: readable text size, clear spacing, and audio you can pause. This is the distinguishable side of perceivable.

Ask of every piece of content: can someone sense this without my eyes or ears? If not, you owe them an alternative.

Let us test the Perceivable principle.

You learned that Perceivable means everyone can sense your content: alt text, captions, transcripts, adaptable layout, and contrast. Sense first, then build on it. 🌱