En réponse à : Stéphane

AudrasJb : Ah, voilà : HTML5 : Techniques for providing useful text alternatives
The figure and figcaption elements provide a method to explicitly associate a caption with with a variety of content including images. Any content inside the figure element that is not contained within the figcaption element is labelled by the content of the figcaption element. The figcaption content may be an adjunct to the text alternative provided using the alt attribute :
The figcaption content may be a text alternative for the image, obviating the need for a text alternative provided using the alt (...)