# Rule Descriptions ## Table of Contents - [WCAG 2.0 Level A & AA Rules](#wcag-20-level-a--aa-rules) - [WCAG 2.1 Level A & AA Rules](#wcag-21-level-a--aa-rules) - [Best Practices Rules](#best-practices-rules) - [Experimental Rules](#experimental-rules) - [Deprecated Rules](#deprecated-rules) ## WCAG 2.0 Level A & AA Rules | Rule ID | Description | Impact | Tags | Issue Type | | :------------------------------------------------------------------------------------------------------------------------------- | :------------------------------------------------------------------------------------------------------------ | :---------------- | :------------------------------------------------------------------------------------ | :------------------------- | | [area-alt](https://dequeuniversity.com/rules/axe/4.0/area-alt?application=RuleDescription) | Ensures <area> elements of image maps have alternate text | Critical | cat.text-alternatives, wcag2a, wcag111, wcag244, wcag412, section508, section508.22.a | failure, needs review | | [aria-allowed-attr](https://dequeuniversity.com/rules/axe/4.0/aria-allowed-attr?application=RuleDescription) | Ensures ARIA attributes are allowed for an element's role | Critical | cat.aria, wcag2a, wcag412 | failure | | [aria-hidden-body](https://dequeuniversity.com/rules/axe/4.0/aria-hidden-body?application=RuleDescription) | Ensures aria-hidden='true' is not present on the document body. | Critical | cat.aria, wcag2a, wcag412 | failure | | [aria-hidden-focus](https://dequeuniversity.com/rules/axe/4.0/aria-hidden-focus?application=RuleDescription) | Ensures aria-hidden elements do not contain focusable elements | Serious | cat.name-role-value, wcag2a, wcag412, wcag131 | failure, needs review | | [aria-input-field-name](https://dequeuniversity.com/rules/axe/4.0/aria-input-field-name?application=RuleDescription) | Ensures every ARIA input field has an accessible name | Moderate, Serious | wcag2a, wcag412 | failure, needs review | | [aria-required-attr](https://dequeuniversity.com/rules/axe/4.0/aria-required-attr?application=RuleDescription) | Ensures elements with ARIA roles have all required ARIA attributes | Critical | cat.aria, wcag2a, wcag412 | failure | | [aria-required-children](https://dequeuniversity.com/rules/axe/4.0/aria-required-children?application=RuleDescription) | Ensures elements with an ARIA role that require child roles contain them | Critical | cat.aria, wcag2a, wcag131 | failure, needs review | | [aria-required-parent](https://dequeuniversity.com/rules/axe/4.0/aria-required-parent?application=RuleDescription) | Ensures elements with an ARIA role that require parent roles are contained by them | Critical | cat.aria, wcag2a, wcag131 | failure | | [aria-roledescription](https://dequeuniversity.com/rules/axe/4.0/aria-roledescription?application=RuleDescription) | Ensure aria-roledescription is only used on elements with an implicit or explicit role | Serious | cat.aria, wcag2a, wcag412 | failure, needs review | | [aria-roles](https://dequeuniversity.com/rules/axe/4.0/aria-roles?application=RuleDescription) | Ensures all elements with a role attribute use a valid value | Serious, Critical | cat.aria, wcag2a, wcag412 | failure | | [aria-toggle-field-name](https://dequeuniversity.com/rules/axe/4.0/aria-toggle-field-name?application=RuleDescription) | Ensures every ARIA toggle field has an accessible name | Moderate, Serious | wcag2a, wcag412 | failure, needs review | | [aria-valid-attr-value](https://dequeuniversity.com/rules/axe/4.0/aria-valid-attr-value?application=RuleDescription) | Ensures all ARIA attributes have valid values | Critical | cat.aria, wcag2a, wcag412 | failure, needs review | | [aria-valid-attr](https://dequeuniversity.com/rules/axe/4.0/aria-valid-attr?application=RuleDescription) | Ensures attributes that begin with aria- are valid ARIA attributes | Critical | cat.aria, wcag2a, wcag412 | failure | | [audio-caption](https://dequeuniversity.com/rules/axe/4.0/audio-caption?application=RuleDescription) | Ensures <audio> elements have captions | Critical | cat.time-and-media, wcag2a, wcag121, section508, section508.22.a | needs review | | [blink](https://dequeuniversity.com/rules/axe/4.0/blink?application=RuleDescription) | Ensures <blink> elements are not used | Serious | cat.time-and-media, wcag2a, wcag222, section508, section508.22.j | failure | | [button-name](https://dequeuniversity.com/rules/axe/4.0/button-name?application=RuleDescription) | Ensures buttons have discernible text | Critical | cat.name-role-value, wcag2a, wcag412, section508, section508.22.a | failure, needs review | | [bypass](https://dequeuniversity.com/rules/axe/4.0/bypass?application=RuleDescription) | Ensures each page has at least one mechanism for a user to bypass navigation and jump straight to the content | Serious | cat.keyboard, wcag2a, wcag241, section508, section508.22.o | failure | | [color-contrast](https://dequeuniversity.com/rules/axe/4.0/color-contrast?application=RuleDescription) | Ensures the contrast between foreground and background colors meets WCAG 2 AA contrast ratio thresholds | Serious | cat.color, wcag2aa, wcag143 | failure, needs review | | [definition-list](https://dequeuniversity.com/rules/axe/4.0/definition-list?application=RuleDescription) | Ensures <dl> elements are structured correctly | Serious | cat.structure, wcag2a, wcag131 | failure | | [dlitem](https://dequeuniversity.com/rules/axe/4.0/dlitem?application=RuleDescription) | Ensures <dt> and <dd> elements are contained by a <dl> | Serious | cat.structure, wcag2a, wcag131 | failure | | [document-title](https://dequeuniversity.com/rules/axe/4.0/document-title?application=RuleDescription) | Ensures each HTML document contains a non-empty <title> element | Serious | cat.text-alternatives, wcag2a, wcag242, ACT | failure | | [duplicate-id-active](https://dequeuniversity.com/rules/axe/4.0/duplicate-id-active?application=RuleDescription) | Ensures every id attribute value of active elements is unique | Serious | cat.parsing, wcag2a, wcag411 | failure | | [duplicate-id-aria](https://dequeuniversity.com/rules/axe/4.0/duplicate-id-aria?application=RuleDescription) | Ensures every id attribute value used in ARIA and in labels is unique | Critical | cat.parsing, wcag2a, wcag411 | failure | | [duplicate-id](https://dequeuniversity.com/rules/axe/4.0/duplicate-id?application=RuleDescription) | Ensures every id attribute value is unique | Minor | cat.parsing, wcag2a, wcag411 | failure | | [form-field-multiple-labels](https://dequeuniversity.com/rules/axe/4.0/form-field-multiple-labels?application=RuleDescription) | Ensures form field does not have multiple label elements | Moderate | cat.forms, wcag2a, wcag332 | needs review | | [frame-title](https://dequeuniversity.com/rules/axe/4.0/frame-title?application=RuleDescription) | Ensures <iframe> and <frame> elements contain a non-empty title attribute | Serious | cat.text-alternatives, wcag2a, wcag241, wcag412, section508, section508.22.i | failure, needs review | | [html-has-lang](https://dequeuniversity.com/rules/axe/4.0/html-has-lang?application=RuleDescription) | Ensures every HTML document has a lang attribute | Serious | cat.language, wcag2a, wcag311, ACT | failure | | [html-lang-valid](https://dequeuniversity.com/rules/axe/4.0/html-lang-valid?application=RuleDescription) | Ensures the lang attribute of the <html> element has a valid value | Serious | cat.language, wcag2a, wcag311, ACT | failure | | [html-xml-lang-mismatch](https://dequeuniversity.com/rules/axe/4.0/html-xml-lang-mismatch?application=RuleDescription) | Ensure that HTML elements with both valid lang and xml:lang attributes agree on the base language of the page | Moderate | cat.language, wcag2a, wcag311, ACT | failure | | [image-alt](https://dequeuniversity.com/rules/axe/4.0/image-alt?application=RuleDescription) | Ensures <img> elements have alternate text or a role of none or presentation | Critical | cat.text-alternatives, wcag2a, wcag111, section508, section508.22.a | failure, needs review | | [input-button-name](https://dequeuniversity.com/rules/axe/4.0/input-button-name?application=RuleDescription) | Ensures input buttons have discernible text | Critical | cat.name-role-value, wcag2a, wcag412, section508, section508.22.a | failure, needs review | | [input-image-alt](https://dequeuniversity.com/rules/axe/4.0/input-image-alt?application=RuleDescription) | Ensures <input type="image"> elements have alternate text | Critical | cat.text-alternatives, wcag2a, wcag111, section508, section508.22.a, ACT | failure, needs review | | [label](https://dequeuniversity.com/rules/axe/4.0/label?application=RuleDescription) | Ensures every form element has a label | Minor, Critical | cat.forms, wcag2a, wcag412, wcag131, section508, section508.22.n | failure, needs review | | [link-name](https://dequeuniversity.com/rules/axe/4.0/link-name?application=RuleDescription) | Ensures links have discernible text | Serious | cat.name-role-value, wcag2a, wcag412, wcag244, section508, section508.22.a | failure, needs review | | [list](https://dequeuniversity.com/rules/axe/4.0/list?application=RuleDescription) | Ensures that lists are structured correctly | Serious | cat.structure, wcag2a, wcag131 | failure | | [listitem](https://dequeuniversity.com/rules/axe/4.0/listitem?application=RuleDescription) | Ensures <li> elements are used semantically | Serious | cat.structure, wcag2a, wcag131 | failure | | [marquee](https://dequeuniversity.com/rules/axe/4.0/marquee?application=RuleDescription) | Ensures <marquee> elements are not used | Serious | cat.parsing, wcag2a, wcag222 | failure | | [meta-refresh](https://dequeuniversity.com/rules/axe/4.0/meta-refresh?application=RuleDescription) | Ensures <meta http-equiv="refresh"> is not used | Critical | cat.time-and-media, wcag2a, wcag2aaa, wcag221, wcag224, wcag325 | failure | | [object-alt](https://dequeuniversity.com/rules/axe/4.0/object-alt?application=RuleDescription) | Ensures <object> elements have alternate text | Serious | cat.text-alternatives, wcag2a, wcag111, section508, section508.22.a | failure, needs review | | [role-img-alt](https://dequeuniversity.com/rules/axe/4.0/role-img-alt?application=RuleDescription) | Ensures [role='img'] elements have alternate text | Serious | cat.text-alternatives, wcag2a, wcag111, section508, section508.22.a | failure, needs review | | [scrollable-region-focusable](https://dequeuniversity.com/rules/axe/4.0/scrollable-region-focusable?application=RuleDescription) | Elements that have scrollable content should be accessible by keyboard | Moderate | wcag2a, wcag211 | failure | | [server-side-image-map](https://dequeuniversity.com/rules/axe/4.0/server-side-image-map?application=RuleDescription) | Ensures that server-side image maps are not used | Minor | cat.text-alternatives, wcag2a, wcag211, section508, section508.22.f | needs review | | [svg-img-alt](https://dequeuniversity.com/rules/axe/4.0/svg-img-alt?application=RuleDescription) | Ensures svg elements with an img, graphics-document or graphics-symbol role have an accessible text | Serious | cat.text-alternatives, wcag2a, wcag111, section508, section508.22.a | failure, needs review | | [td-headers-attr](https://dequeuniversity.com/rules/axe/4.0/td-headers-attr?application=RuleDescription) | Ensure that each cell in a table using the headers refers to another cell in that table | Serious | cat.tables, wcag2a, wcag131, section508, section508.22.g | failure, needs review | | [th-has-data-cells](https://dequeuniversity.com/rules/axe/4.0/th-has-data-cells?application=RuleDescription) | Ensure that each table header in a data table refers to data cells | Serious | cat.tables, wcag2a, wcag131, section508, section508.22.g | failure, needs review | | [valid-lang](https://dequeuniversity.com/rules/axe/4.0/valid-lang?application=RuleDescription) | Ensures lang attributes have valid values | Serious | cat.language, wcag2aa, wcag312 | failure | | [video-caption](https://dequeuniversity.com/rules/axe/4.0/video-caption?application=RuleDescription) | Ensures <video> elements have captions | Critical | cat.text-alternatives, wcag2a, wcag122, section508, section508.22.a | needs review | ## WCAG 2.1 Level A & AA Rules | Rule ID | Description | Impact | Tags | Issue Type | | :----------------------------------------------------------------------------------------------------------------- | :-------------------------------------------------------------------------------------------- | :------ | :--------------------------- | :--------- | | [autocomplete-valid](https://dequeuniversity.com/rules/axe/4.0/autocomplete-valid?application=RuleDescription) | Ensure the autocomplete attribute is correct and suitable for the form field | Serious | cat.forms, wcag21aa, wcag135 | failure | | [avoid-inline-spacing](https://dequeuniversity.com/rules/axe/4.0/avoid-inline-spacing?application=RuleDescription) | Ensure that text spacing set through style attributes can be adjusted with custom stylesheets | Serious | wcag21aa, wcag1412 | failure | ## Best Practices Rules Rules that do not necessarily conform to WCAG success criterion but are industry accepted practices that improve the user experience. | Rule ID | Description | Impact | Tags | Issue Type | | :----------------------------------------------------------------------------------------------------------------------------------------------- | :--------------------------------------------------------------------------------------------------- | :----------------- | :----------------------------------------- | :------------------------- | | [accesskeys](https://dequeuniversity.com/rules/axe/4.0/accesskeys?application=RuleDescription) | Ensures every accesskey attribute value is unique | Serious | best-practice, cat.keyboard | failure | | [aria-allowed-role](https://dequeuniversity.com/rules/axe/4.0/aria-allowed-role?application=RuleDescription) | Ensures role attribute has an appropriate value for the element | Minor | cat.aria, best-practice | failure, needs review | | [empty-heading](https://dequeuniversity.com/rules/axe/4.0/empty-heading?application=RuleDescription) | Ensures headings have discernible text | Minor | cat.name-role-value, best-practice | failure, needs review | | [frame-tested](https://dequeuniversity.com/rules/axe/4.0/frame-tested?application=RuleDescription) | Ensures <iframe> and <frame> elements contain the axe-core script | Critical | cat.structure, review-item, best-practice | failure, needs review | | [frame-title-unique](https://dequeuniversity.com/rules/axe/4.0/frame-title-unique?application=RuleDescription) | Ensures <iframe> and <frame> elements contain a unique title attribute | Serious | cat.text-alternatives, best-practice | failure | | [heading-order](https://dequeuniversity.com/rules/axe/4.0/heading-order?application=RuleDescription) | Ensures the order of headings is semantically correct | Moderate | cat.semantics, best-practice | failure | | [identical-links-same-purpose](https://dequeuniversity.com/rules/axe/4.0/identical-links-same-purpose?application=RuleDescription) | Ensure that links with the same accessible name serve a similar purpose | Minor | wcag2aaa, wcag249, best-practice | needs review | | [image-redundant-alt](https://dequeuniversity.com/rules/axe/4.0/image-redundant-alt?application=RuleDescription) | Ensure image alternative is not repeated as text | Minor | cat.text-alternatives, best-practice | failure | | [label-title-only](https://dequeuniversity.com/rules/axe/4.0/label-title-only?application=RuleDescription) | Ensures that every form element is not solely labeled using the title or aria-describedby attributes | Serious | cat.forms, best-practice | failure | | [landmark-banner-is-top-level](https://dequeuniversity.com/rules/axe/4.0/landmark-banner-is-top-level?application=RuleDescription) | Ensures the banner landmark is at top level | Moderate | cat.semantics, best-practice | failure | | [landmark-complementary-is-top-level](https://dequeuniversity.com/rules/axe/4.0/landmark-complementary-is-top-level?application=RuleDescription) | Ensures the complementary landmark or aside is at top level | Moderate | cat.semantics, best-practice | failure | | [landmark-contentinfo-is-top-level](https://dequeuniversity.com/rules/axe/4.0/landmark-contentinfo-is-top-level?application=RuleDescription) | Ensures the contentinfo landmark is at top level | Moderate | cat.semantics, best-practice | failure | | [landmark-main-is-top-level](https://dequeuniversity.com/rules/axe/4.0/landmark-main-is-top-level?application=RuleDescription) | Ensures the main landmark is at top level | Moderate | cat.semantics, best-practice | failure | | [landmark-no-duplicate-banner](https://dequeuniversity.com/rules/axe/4.0/landmark-no-duplicate-banner?application=RuleDescription) | Ensures the document has at most one banner landmark | Moderate | cat.semantics, best-practice | failure | | [landmark-no-duplicate-contentinfo](https://dequeuniversity.com/rules/axe/4.0/landmark-no-duplicate-contentinfo?application=RuleDescription) | Ensures the document has at most one contentinfo landmark | Moderate | cat.semantics, best-practice | failure | | [landmark-no-duplicate-main](https://dequeuniversity.com/rules/axe/4.0/landmark-no-duplicate-main?application=RuleDescription) | Ensures the document has at most one main landmark | Moderate | cat.semantics, best-practice | failure | | [landmark-one-main](https://dequeuniversity.com/rules/axe/4.0/landmark-one-main?application=RuleDescription) | Ensures the document has a main landmark | Moderate | cat.semantics, best-practice | failure | | [landmark-unique](https://dequeuniversity.com/rules/axe/4.0/landmark-unique?application=RuleDescription) | Landmarks must have a unique role or role/label/title (i.e. accessible name) combination | Moderate | cat.semantics, best-practice | failure | | [meta-viewport-large](https://dequeuniversity.com/rules/axe/4.0/meta-viewport-large?application=RuleDescription) | Ensures <meta name="viewport"> can scale a significant amount | Minor | cat.sensory-and-visual-cues, best-practice | failure | | [meta-viewport](https://dequeuniversity.com/rules/axe/4.0/meta-viewport?application=RuleDescription) | Ensures <meta name="viewport"> does not disable text scaling and zooming | Critical | cat.sensory-and-visual-cues, best-practice | failure | | [page-has-heading-one](https://dequeuniversity.com/rules/axe/4.0/page-has-heading-one?application=RuleDescription) | Ensure that the page, or at least one of its frames contains a level-one heading | Moderate | cat.semantics, best-practice | failure | | [region](https://dequeuniversity.com/rules/axe/4.0/region?application=RuleDescription) | Ensures all page content is contained by landmarks | Moderate | cat.keyboard, best-practice | failure | | [scope-attr-valid](https://dequeuniversity.com/rules/axe/4.0/scope-attr-valid?application=RuleDescription) | Ensures the scope attribute is used correctly on tables | Moderate, Critical | cat.tables, best-practice | failure | | [skip-link](https://dequeuniversity.com/rules/axe/4.0/skip-link?application=RuleDescription) | Ensure all skip links have a focusable target | Moderate | cat.keyboard, best-practice | failure, needs review | | [tabindex](https://dequeuniversity.com/rules/axe/4.0/tabindex?application=RuleDescription) | Ensures tabindex attribute values are not greater than 0 | Serious | cat.keyboard, best-practice | failure | | [table-duplicate-name](https://dequeuniversity.com/rules/axe/4.0/table-duplicate-name?application=RuleDescription) | Ensure that tables do not have the same summary and caption | Minor | cat.tables, best-practice | failure | ## Experimental Rules Rules we are still testing and developing. They are not enabled by default in axe-core, but are enabled for the axe browser extensions. | Rule ID | Description | Impact | Tags | Issue Type | | :------------------------------------------------------------------------------------------------------------------------------- | :-------------------------------------------------------------------------------------------------------------------------------------------------- | :------- | :--------------------------------------------------------------------- | :------------------------- | | [css-orientation-lock](https://dequeuniversity.com/rules/axe/4.0/css-orientation-lock?application=RuleDescription) | Ensures content is not locked to any specific display orientation, and the content is operable in all display orientations | Serious | cat.structure, wcag134, wcag21aa, experimental | failure, needs review | | [focus-order-semantics](https://dequeuniversity.com/rules/axe/4.0/focus-order-semantics?application=RuleDescription) | Ensures elements in the focus order have an appropriate role | Minor | cat.keyboard, best-practice, experimental | failure | | [hidden-content](https://dequeuniversity.com/rules/axe/4.0/hidden-content?application=RuleDescription) | Informs users about hidden content. | Minor | cat.structure, experimental, review-item, best-practice | failure, needs review | | [label-content-name-mismatch](https://dequeuniversity.com/rules/axe/4.0/label-content-name-mismatch?application=RuleDescription) | Ensures that elements labelled through their content must have their visible text as part of their accessible name | Serious | wcag21a, wcag253, experimental | failure | | [link-in-text-block](https://dequeuniversity.com/rules/axe/4.0/link-in-text-block?application=RuleDescription) | Links can be distinguished without relying on color | Serious | cat.color, experimental, wcag2a, wcag141 | failure, needs review | | [no-autoplay-audio](https://dequeuniversity.com/rules/axe/4.0/no-autoplay-audio?application=RuleDescription) | Ensures <video> or <audio> elements do not autoplay audio for more than 3 seconds without a control mechanism to stop or mute the audio | Moderate | wcag2a, wcag142, experimental | failure, needs review | | [p-as-heading](https://dequeuniversity.com/rules/axe/4.0/p-as-heading?application=RuleDescription) | Ensure p elements are not used to style headings | Serious | cat.semantics, wcag2a, wcag131, experimental | failure | | [table-fake-caption](https://dequeuniversity.com/rules/axe/4.0/table-fake-caption?application=RuleDescription) | Ensure that tables with a caption use the <caption> element. | Serious | cat.tables, experimental, wcag2a, wcag131, section508, section508.22.g | failure | | [td-has-header](https://dequeuniversity.com/rules/axe/4.0/td-has-header?application=RuleDescription) | Ensure that each non-empty data cell in a large table has one or more table headers | Critical | cat.tables, experimental, wcag2a, wcag131, section508, section508.22.g | failure | ## Deprecated Rules Deprecated rules are not enabled by default and will be removed in the next major release. _There are no matching rules_