El atributo alt en la Wikipedia

Curioso, el atributo alt tiene su propio artículo en la Wikipedia en inglés: alt attribute. El artículo dice:

The alt attribute is used in HTML and XHTML documents to specify alternative text (alt text) that is to be rendered when the element to which it is applied cannot be rendered. It is also used by "screen reader" software so that a person who is listening to the content of a webpage (for instance, a person who is blind) can interact with this element. The attribute was introduced in HTML 2 and in HTML 4.01 was required for the img and area tags. It is optional for the input tag and the deprecated applet tag.