In October 2021, the IPTC announced new metadata properties to make images more accessible. One particularly interesting one is the AltText property, which is intended to hold the same kind of information that you'd see in the alt attribute of images on the web. Properly-written alt-text is usually a description of the image intended to let partially-sighted or blind users know what is shown in the image. AltText is different from the Title or Description of an image; it's a description of the appearance of an image, rather than a description of what the image represents. So, for example, if you took Robert Capa's famous 'Falling Soldier' image, the title might be "Falling Soldier" or "Loyalist Militiaman at the Moment of Death", the description might be "Photograph by Robert Capa allegedly showing a militiaman shot at the battle of Cerro Muriano, 1936", but the alt-text might be "A black-and-white photograph of a man in civilian clothes with a leather cartridge belt falling backwards, dropping his rifle from his outstretched right hand as he falls." (maybe not the best description; writing good alt-text is tricky).
For users like myself who use Lightroom as part of their website creation workflow, it would be extremely useful to have proper support for AltText in Lightroom. Support for website accessibility through features such as alt-text is seen as increasingly important, and more and more web tools will probably be updated to use text from the AltText property to populate the alt attribute of images in future.