ARIA is a set of attributes that tell assistive technology an element's role, state, and relationships. The key word is tell. ARIA draws nothing and adds no behavior: it changes only how an element appears in the accessibility API - the accessibility tree the browser builds for screen readers. A newcomer to accessibility reacts naturally: sprinkling the markup with attributes - a role here, an aria-label there, an aria-hidden wherever something is in the way. It feels like more ARIA means more accessible. In practice the opposite.

The first rule of ARIA: if a native HTML element or attribute already provides the semantics and behavior you need, use it instead of repurposing another tag with a role. Behind the rule sits a sobering statistic: in WebAIM's survey of a million home pages, pages with ARIA averaged noticeably more accessibility errors than pages without it. Hence the saying: no ARIA is better than bad ARIA. The reason is simple: a native button brings focusability, Enter and Space handling, the button role, and correct state - free, in every browser. Replace it with a div carrying role=button and the whole baggage must be reproduced by hand.

This is where the main trap hides. A declared role is not decoration - it is a contract. Declare role=dialog and you owe focus trapping in the window, returning focus to the trigger on close, and Escape handling. Declare role=tab and you take on arrow-key navigation and managing aria-selected. ARIA describes what an element pretends to be, but delivering the promise is your code's job. A screen reader announces a div with role=button as a button, the user presses Enter and gets nothing: there is no handler. That is worse than an honest, unannounced div - the interface has lied.

ARIA has three kinds of attributes, and telling them apart helps. A role sets the object type - a dialog, a tab, a status. A state describes a changeable condition - whether a list is expanded, whether an item is selected. A property records a relationship or characteristic - which element the button controls, which heading names it.