Accessibility and HTML5: Semantic Elements and More

A div for everything and everything is in its div…

If you’ve been working on websites for a while, you’ve no doubt had a few that seem to be just div after div, where the div explosion serves to place or style each part of the page as needed. The problem is, a div by itself doesn’t tell the user (or, more to the point, the user agent) anything about what the div contains, and the styling is likely to be lost on someone using a screen reader.

In HTML5, we have the semantic elements, which generally act like divs – they’re block elements that contain other elements – but also provide meaning; each tag describes what it contains, which allows a user agent (such as a screen reader) to handle it appropriately. We still use divs, when no semantic element is appropriate, but they should no longer be the first choice. The semantic elements include:

  • <nav> encloses a navigation block; this will often contain a list of links, but not every list of links needs to belong to a nav. Screen readers may be able to go directly to the nav section or skip it if not needed.
  • <main> is for the main content of the document; it should contain only content that is unique to that document, not content repeated across multiple pages. User agents will often be able to navigate directly to the main content block, bypassing navigation links. At most one main element should exist in a given document, and it cannot descend from an article, aside, header, footer, or nav element.
  • <article> describes a self-contained block; it could be moved to another page and still make sense on its own. A page that consists of one self-contained block of content will simply hold it inside a <main> element, but multiple blocks that do not depend on each other will be <article>s instead. An <article> can contain other <article>s that are related to it, such as comments on a story.
  •  <aside> contains information which is tangentially related to the primary content, but isn’t required to understand it; this content is likely to be visually represented as a sidebar or pull quote.
  • <figure> encloses some self-contained content, which may be (but is not required to be) graphical in nature. Each <figure> may contain one <figcaption>, which provides a caption for everything contained in the figure; this groups all of the contents and provides a way to refer to them even if the page layout changes.
  • <section> is a…er…section of the document; it groups together part of the document, such as a chapter. Sections generally come with headers and should contain content that logically belongs together.

If none of the above signpost elements are appropriate, then we look for a more specific element, such as <address>, <blockquote>, or even <p>. Only if the content doesn’t have any semantics do we use the plain <div>. It’s a bit more work, but it allows the user agent to process each type of content according to its own rules, according to the user’s desires.

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