Caption should be provided with every image used to present content, either underneath it or in a body of text that is relevant to it, if used to complement a story. Figure 6.35 shows part of the photo gallery of the website of a yearly tennis competition, in which this principle was not applied when the page was active. A series of images were simply presented, along with navigational aid that allowed linear or nonlinear navigation of the images. Although the images used as part of the background required no labeling, those used for content would have benefited from a brief description placed, for example, at the bottom. This would, no doubt, save those who did not know the player from wondering who she was and who she was playing at that moment.
Source: Sklar David (2016), HTML: A Gentle Introduction to the Web’s Most Popular Language, O’Reilly Media; 1st edition.