Axe Core Guide
Free site validation
Find out what web pages on your sites are affected by HTML issues.
It is a best practice to make sure each heading element, denoted by the tags <h1> through <h6>, contains text.
Users of screen readers are informed when a heading tag is present. Users may become confused or even unable to access information on the page’s structure if the headline is blank or the text cannot be accessible.
Users of this technology won’t be able to hear the content of a header if the text inside it is inaccessible to a screen reader. Users using screen readers must be able to access the contents since headings reveal the structure of a webpage.
Applying header markup (<h1> through <h6>) is a quick approach to make content stand out, but doing so will make it more difficult for those using assistive technology to navigate a website.
Due to the fact that search engines use headings when filtering, arranging, and showing results, headers offer advantages beyond just making a page more accessible. Making your website more searchable is another benefit of making it more accessible.
Users of screen readers can navigate between headings in the same manner that sighted users might skim a page to gain a sense of its contents. Users, especially those who use screen readers, can save a ton of time and stress by using well-written, logically-arranged headings.
What this Accessibility Rule Checks
Ensures that headings have content and that a screen reader can access that content.
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Related Accessibility Rules
WAI-ARIA role attribute values must be correct. This means that values must be written correctly, correlate to existing ARIA role values, and not be abstract roles in order to properly display the element’s purpose.
When an assigned WAI-ARIA role value for the parent element is invalid, a developer’s intended accessible technology activity is disabled.
When screen readers and other assistive devices do not understand the job of each element on a web page, they cannot interact with it intelligently or explain the role to the user. When the value for a role is invalid, assistive technologies are unable to communicate the element’s features, properties, and methods. Applying role="table" to a <ul>, for example, effectively hijacks the default semantics associated with the <ul> element in a way that screenreaders do not expect, resulting in unexpected behavior.
What this Accessibility Rule Checks
Check all elements with WAI-ARIA role attribute values to confirm the role value is correct. The role value must be appropriate for the element in the context of the document.
Whether native HTML or a custom widget, user input elements need to play the right roles in order to make their meaning clear to screen reader users when they are focused on and landed on. If a custom widget, the element’s function must be correctly exposed by using appropriate ARIA role values rather than abstract roles.
In order for screen reader technology to convey information to users, elements in the focus order must play a function appropriate for interactive content.
If interactive content elements do not have the proper roles, the developer’s planned accessibility function cannot be carried out by the role.
When screen readers and other assistive technologies cannot communicate to the user the proper role of each element on the web page, they are unable to interact with it sensibly. Assistive technology cannot communicate with an HTML element’s set of features, properties, and ways of communicating information to and/or from the user when the value for a role is invalid.
What this Accessibility Rule Checks
Verifies that the role attribute value is accurate and suitable for all interactive components in the focus order, regardless of whether they are native HTML or customized ARIA widgets.
ARIA role values must be assigned valid values. Role values must be appropriately written, correlate to existing ARIA role values, and not be abstract roles in order to correctly display the element’s purpose.
Assistive technologies do not read elements with erroneous ARIA role values as intended by the developer.
When screen readers and other assistive devices do not know the function of each element on a web page, they are unable to interact with or communicate the function to the user. When a role value is invalid, an element’s characteristics, properties, and ways of transmitting information to and/or from the user can be communicated via assistive technologies.
What this Accessibility Rule Checks
Examines each element containing the WAI-ARIA role property to check that its value is valid.
The h1 through h6 element tags must be in a sequentially-descending order for headings to be in a correct logical order.
The fundamental goal of headers is to communicate the page’s organizational structure. The same goal is served by employing various font sizes for sighted users.
For screen reader users, however, text size is useless because a screen reader can only recognize a header if it is correctly marked up. When header components are used correctly, both sighted and screen reader users will find it much simpler to traverse the page.
Users of screen readers can navigate between headings in the same manner that sighted users might skim a page to gain a sense of its contents. Users, especially those who use screen readers, can save a ton of time and stress by using well-written, logically-arranged headings.
Headings serve to explain the organization of the webpage, not only to draw attention to key text. They ought to be succinct, distinct, and accompanied by h1 through h6 components used in hierarchical order. Headings are useful tools for screen reader users because of all of these characteristics. Screen reader users can move among headings in a manner akin to how sighted readers can quickly scan a page and get a sense of its content. Screen readers can save time and stress by using headings that are clearly written and arranged.
Since search engines employ headings when filtering, arranging, and showing results, headings offer other advantages outside just making the page more easily accessible. Making your website more searchable is another benefit of making it more accessible.
What this Accessibility Rule Checks
Ensures the semantic accuracy of the headings’ order.
When button and link text in an alt property value repeats, screen reader users hear the same information twice, rendering the alt text worthless and confusing.
It is redundant and potentially misleading to have alternate text for a link or image repeated in text adjacent to the link or image because a screen reader would read it twice.
Because image buttons employ alt attributes for labels, the labels should not repeat the text next to the button. Screen readers announce the text to the user twice when there is duplicate alternative text for an image or link in the text adjacent to that image or link.
What this Accessibility Rule Checks
Make certain that the button and link text are not repeated as picture alternatives.
Using the title or aria-describedby properties, form <input> elements may be given titles (but not both).
The purpose of these qualities is to convey more information, such as a tip.
These properties are used to convey additional information, such as a hint. Hints are exposed differently to accessibility APIs than labels, which can cause issues with assistive technologies.
When form inputs such as text entry fields, radio buttons, check boxes, and select menus do not have labels other than the title and aria-describedby attribute values, screen readers perceive the material as advisory only. The labels provided by the title and aria-describedby attributes are insufficient to create a real label that can be inferred programmatically from the input form element’s code.
What this Accessibility Rule Checks
Ensures that every <input> that requires a label has a label other than title or aria-describedby.
Each form element must have a label element attached with it programmatically.
Forms must have effective form labels in order to be accessible. Form elements like as checkboxes, radio buttons, input fields, etc. are frequently self-explanatory to sighted users, even if they are not programmatically labeled. Users with screen readers require descriptive form labels to identify form fields. Adding labels to all form elements removes uncertainty and makes the product more accessible.
When form elements lack labels, screen reader users are unaware of the expected data input. Screen readers cannot determine information about input items programmatically in the absence of an established label association (or redundant text functioning as a label).
Since clicking the label activates the control, people with weak motor control do not benefit from a bigger clickable area for the control.
What this Accessibility Rule Checks
Ensures that each form element has a label associated with it programmatically.
Ensures the complementary landmark or aside is at top level.
Complementary content is content that supports the primary idea of a page or document. Users of screen readers have the option to bypass supplemental content that shows at the accessibility API’s top level. Embedding an <aside> element within another landmark may prevent the ability for screen reader users to browse through supplemental content.
What this Accessibility Rule Checks
Do not insert <aside> elements or elements containing role="complementary" inside landmark-marked content.
Best practice dictates that the primary landmark should not be enclosed within another landmark. All content must be contained within discrete areas, such as the header (role="banner"), body (role="main"), and footer (role="contentinfo").
Screen reader users can navigate a website much more easily if the content is divided into several high-level categories. It is difficult to locate content outside of these categories, and its purpose may be obscure.
Historically, HTML lacked essential semantic markers, such as the ability to define page sections as the header, navigation, primary content, and footer. Using both HTML5 elements and ARIA landmarks in the same element is considered an excellent practice, but as browser compatibility improves, HTML regions will likely become more popular in the future.
HTML Living Standard says “A hierarchically correct main element is one whose ancestor elements are limited to <html>, <body>, <div>, <form> without an accessible name, and autonomous custom elements. Each main element must be a hierarchically correct main element”. This may be a “recommended practice” according to W3C validation.
What this Accessibility Rule Checks
Ensures that all page content falls within a landmark region.
The core content of the page should only have one main landmark, and if the page contains iframe components, each one should either have no landmarks or just one. This is considered best practice.
If all of the content is divided up into one or more high-level divisions, screen reader users will have much easier time navigating a website. Outside of these categories, information can be hard to access and has an uncertain purpose.
Some essential semantic markers, such the ability to designate portions of the page as the header, navigation, primary content, and footer, have historically been absent from HTML. Although it’s recommended to combine HTML5 elements with ARIA markers in a single element, HTML regions will eventually prevail as browser support grows.
What this Accessibility Rule Checks
Makes sure there is just one primary landmark in the document.