ARIA, which stands for Accessible Rich Internet Applications, is a set of HTML attributes defined by the W3C that allows developers to communicate the roles, states, and properties of user interface elements to assistive technologies such as screen readers. Where standard HTML falls short in describing complex, dynamic interface components, ARIA provides the supplementary layer of meaning that makes those components understandable to users who rely on assistive software.
Why ARIA Exists
Modern web applications frequently use interactive components — custom dropdowns, modal dialogs, tab panels, sliders — that have no native HTML equivalent. A <div> styled to look and behave like a button, for instance, carries no inherent meaning for a screen reader. ARIA bridges this gap by letting developers annotate elements with semantic information that the browser passes to the operating system's accessibility APIs, which assistive technologies then interpret and convey to the user.
It is worth noting that ARIA does not change the visual appearance of an element, nor does it alter its behavior in a browser. Its sole purpose is to enrich the accessibility tree — the structured representation of a page that assistive technologies consume.
How ARIA Attributes Work
ARIA attributes fall into three broad categories. Roles define what an element is, such as role="dialog" or role="navigation". Properties describe characteristics of an element that do not change frequently, for example aria-label or aria-required. States convey dynamic conditions that may change as a user interacts with the page, such as aria-expanded="true" on a collapsible menu or aria-checked="false" on a custom checkbox.
Together, these attributes allow a developer to construct a rich, accurate description of an interface that assistive technologies can announce and navigate. For example, a custom tab component built from generic <div> elements can be made fully accessible by assigning role="tablist", role="tab", and aria-selected attributes to the appropriate elements.
ARIA and Semantic HTML
A foundational principle in accessibility work is that ARIA should supplement semantic HTML, not replace it. Native HTML elements such as <button>, <nav>, and <input> already carry built-in roles and behaviors that browsers and assistive technologies understand without any additional attributes. Using these elements correctly — an approach known as semantic HTML — is always preferable to recreating their functionality with ARIA on generic elements.
The W3C summarizes this hierarchy with the first rule of ARIA use: if a native HTML element or attribute already provides the required semantics and behavior, use it instead of repurposing another element and adding ARIA. ARIA is most valuable when native HTML genuinely cannot express the complexity of a custom component or when dynamic state changes need to be communicated after the page has loaded.
Properly applied, ARIA is a powerful tool for building inclusive web experiences. Misapplied, it can create confusion for assistive technology users by overriding correct semantics with incorrect ones. Understanding when and how to use it is therefore a core competency in web accessibility.