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Screen readers need language information to switch between pronunciation libraries. Without a specified language, screen readers default to the user's preferred language, resulting in incorrect pronunciation that sounds like a strange accent and makes content difficult or impossible to understand.

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Screen readers use language-specific sound libraries for proper pronunciation. Invalid language attributes cause screen readers to use the wrong library, making text sound like a confusing accent or completely unintelligible, especially for multilingual users who access content in multiple languages.

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Content should be organized within high-level landmark regions like <header>, <navigation>, <main>, and <footer>. Content outside these sections is difficult to find and its purpose may be unclear, making navigation inefficient for screen reader users who rely on landmarks to understand page structure.

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Touch targets must be large enough or spaced far enough apart to be activated without accidentally hitting adjacent controls. This helps users on mobile devices, people with hand tremors or mobility impairments, users in shaking environments like public transit, and anyone using one hand or large fingers to interact with the interface.

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Duplicating alternative text adjacent to an image or link forces screen readers to announce the same information twice. This redundancy is unnecessary and confusing, especially when image buttons repeat their labels in nearby text.

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Using ARIA attributes where they're not expected causes unpredictable behavior in assistive technologies. Following the ARIA specification ensures that screen readers and other tools can properly interpret and communicate your content's meaning to people with disabilities.

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Misspelled or non-existent ARIA attributes cannot perform their intended accessibility function. Assistive technologies rely on correctly spelled, current ARIA attributes to convey proper user interface behaviors and structural information to people with disabilities.

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ARIA attributes must contain correctly spelled values that match the attribute's expected options. Invalid values prevent the accessibility feature from working, making content inaccessible to assistive technology users who depend on these attributes for navigation and interaction.

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Invalid ARIA role and HTML element combinations can break accessibility for entire sections of your application. When roles are used incorrectly, assistive technologies may report confusing or nonsensical information to users, making it impossible for them to understand and interact with the interface properly.

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Invalid ARIA role values prevent assistive technologies from understanding and communicating the element's purpose to users. Without valid roles, screen readers cannot provide information about the element's features, properties, or how users should interact with it.

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Setting <body aria-hidden="true" hides all page content from assistive technologies while leaving it visible on screen. This creates a confusing experience where keyboard users can still tab to elements, but screen readers remain completely silent, providing no information about what's focused.

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People who zoom to 400% or use a narrow viewport must be able to scroll in one direction only. A layout that still requires horizontal scrolling at 320 CSS pixels forces magnified readers to pan left and right line by line, which makes the page close to unusable.

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The contentinfo landmark must be at the top level to help screen reader users quickly navigate to footer information. When nested inside another landmark, it becomes harder to find, defeating its purpose of providing quick access to content information.

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Deprecated ARIA roles are not recognized by modern screen readers and assistive technologies. Using outdated roles means some users cannot access essential information or functionality on your site.

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Every page should have exactly one main landmark that identifies the primary content. Without a main landmark, screen reader users must navigate through all content linearly to find what they're looking for, making page navigation difficult and time-consuming.

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Multiple contentinfo landmarks force screen reader users to sort through extra options to find footer information. Each page should have only one content info landmark to enable quick, predictable navigation without overwhelming users with duplicate structural markers.

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Multiple main landmarks confuse screen reader users about where the primary content is located. Each page should have only one main landmark so users can quickly and predictably navigate to the primary content area.

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The page title is the first thing screen reader users hear when loading a page. Without a descriptive, unique title, users must read through the entire page to understand its contents and purpose, wasting valuable time on every page visit.

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Interactive widgets that support name from content must have aria-label or aria-labelledby values that match their visible text. Mismatches confuse voice control users who speak the visible label but activate a different function based on the hidden accessible name.

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People with low vision or color blindness cannot read text that lacks sufficient contrast with its background. With nearly three times more people having low vision than total blindness, and 8% of men and 0.4% of women having color deficiencies, adequate contrast is essential for making text readable to millions of users.

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Using prohibited ARIA attributes prevents important information from reaching assistive technology users. It also causes assistive technologies to behave inconsistently as they attempt to compensate for the error.

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Using ARIA attributes in roles where they're not allowed can disable accessibility for entire sections of your application. Invalid attribute-role combinations create conflicts that cause assistive technologies to report incorrect or nonsensical information about your interface.

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Keyboard users have no pointer to show where they are. The focus indicator is their only cue, and a sticky header, footer, cookie banner, or other author-created overlay that completely hides the focused control strands them with no idea what will activate next.

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Headings convey page structure for screen reader users the same way text size does for sighted users. Properly ordered headings (h1 through h6) allow screen reader users to quickly navigate and understand content structure, saving significant time and frustration while also improving search engine optimization.

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Screen readers announce headings to help users navigate page structure. Empty headings confuse users and prevent them from understanding the page's organization. Headings should only be used to convey structure, not for visual styling, and must contain accessible text that screen readers can announce.

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Screen readers cannot translate images into text without alt attributes. Alternative text is essential for blind users and beneficial for users with low vision or color blindness, providing the same information that sighted users get from viewing the image.

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Nested interactive elements create empty tab stops where screen readers remain silent. When users tab to a focusable element inside another interactive control, they receive no information about its name, role, or state, creating a confusing and broken navigation experience.

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Sighted keyboard users rely on a visible focus indicator to know where they are on the page. When focus styles are missing, too subtle, or have insufficient contrast against the surrounding colors, users cannot tell which element will respond when they press Enter or Space, making keyboard navigation slow and error-prone. This especially affects people with motor impairments who cannot use a mouse and people with low vision who need clear, high-contrast indicators.

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Keyboard users move through a page with Tab, Shift+Tab, arrow keys and Escape. When focus enters a component and none of those keys lets it leave, the rest of the page becomes unreachable and the only way out is to reload or abandon it.

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Each landmark on a page must have either a unique role or a unique accessible name. Duplicate landmarks confuse screen reader users about which section they're navigating to, making it difficult to efficiently move through the page structure.

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Keyboard users and screen reader users can only interact with links that have accessible names and can receive focus. Without proper names, users don't know where links lead. Without keyboard focus, users who cannot use a mouse cannot activate the links at all.

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The main landmark must be at the top level and not nested inside other landmarks. This ensures screen reader users can quickly navigate to the primary content without searching through complex hierarchy, making page navigation simpler and more predictable.

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Keyboard-only users must tab through all navigation and header content before reaching the main content, which can take several minutes and cause physical pain for users with motor limitations. Bypass mechanisms like skip links allow these users to jump directly to main content, saving time and reducing fatigue.

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Screen reader users use keyboard shortcuts to jump directly to the first h1, expecting to land at the main content. Without an h1 or with a misplaced one, users must listen to more of the page to understand its structure, wasting valuable time on every page visit.

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ARIA widget roles need required attributes to describe their current state. Without these attributes, screen readers cannot communicate essential information like whether a checkbox is checked or a slider's current value, leaving users unable to interact effectively with the widget.

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People with low vision and dyslexia increase line height, letter spacing, word spacing, and paragraph spacing so they can read. Fixed-height boxes and overflow: hidden containers clip or overlap that text, which is a loss of content under WCAG 1.4.12.

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The user-scalable="no" and restrictive maximum-scale parameters prevent people with low vision from zooming to read content. Users who rely on browser zoom to enlarge text are blocked from accessing content at a readable size, violating their need to scale pages up to 5x zoom.

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