Web accessibility is not just a moral obligation — it's a quality factor that Google considers in its algorithm, and a growing legal requirement in Europe (Web Accessibility Directive, WCAG 2.1).

Alt Text: Accessibility and SEO

Every image on your site should have a descriptive alt attribute. The reasons are multiple:

  • Users with visual impairments use screen readers that read the alt attribute aloud
  • If an image fails to load, the alt text is displayed instead
  • Google Images indexes images based on their alternative text

An empty alt="" is acceptable for purely decorative images, but any image that conveys meaning must have an informative alt.

Color Contrast

The WCAG 2.1 standard recommends a contrast ratio of at least 4.5:1 between text and its background (level AA). Light gray text on a white background may look elegant, but it's unreadable for someone with a visual impairment — or on a screen in bright sunlight.

Contrast errors affect regular text, buttons, and links alike. A button whose label is barely readable isn't just inaccessible: it converts worse for all users.

ARIA (Accessible Rich Internet Applications)

ARIA attributes (aria-label, aria-describedby, role, etc.) enrich HTML semantics for assistive technologies. They're particularly useful for complex interactive components: modals, accordions, tabs, sliders.

A word of caution: poorly used ARIA does more harm than good. The first rule of ARIA is to use native HTML semantics when they exist — a <button> rather than a <div role="button">.

Links and Buttons Without Visible Text

A button that displays only an SVG icon with no text or aria-label is invisible to screen readers. You must always provide an accessible label: either aria-label="Close" or text hidden visually but announced by assistive technologies.

Accessibility as a Global Quality Signal

Google Lighthouse and PageSpeed Insights integrate an accessibility score in their evaluation. An accessible site is also a better-structured site, easier to maintain, and offers a better experience for all users.

SiteCheck checks alt attributes, links without text, contrast ratios, and the presence of essential ARIA attributes in the Content category of every full audit.