<desc>

The <desc> SVG element provides an accessible, long-text description of any SVG container element or graphics element.

Text in a <desc> element is not rendered as part of the graphic. If the element can be described by visible text, it is possible to reference that text with the aria-describedby attribute. If aria-describedby is used, it will take precedence over <desc>.

The hidden text of a <desc> element can also be concatenated with the visible text of other elements using multiple IDs in an aria-describedby value. In that case, the <desc> element must provide an ID for reference.

html,
body,
svg {
  height: 100%;
}

<svg viewBox="0 0 10 10" xmlns="http://www.w3.org/2000/svg">
  <circle cx="5" cy="5" r="4">
    <desc>
      I'm a circle and that description is here to demonstrate how I can be
      described, but is it really necessary to describe a simple circle like me?
    </desc>
  </circle>
</svg>