figure: image and annotation as a common unit

Useful to know

<figure> denotes a stand-alone content that is regarded as a common unit. It can be an image, chart, sample code or other material . <figcaption> adds an elucidation to this unit. The item is not a mandatory wrapper for every photo on the page. [1]

In a mechanism diagram, the elucidation can explain what the arrows show and which parts are simplified. It is different from the alternative text of the image: the two texts perform related but not identical tasks.

For a decorative background, figure usually does not carry a useful stand-alone structure. For the graph to which the text refers, the group helps to keep the link clear. Check that the clarification describes the actual content and source when needed. The HTML element itself does not give the right to use a foreign image and does not confirm the data in the diagram.