Part of what makes the web so brilliant is in it’s flexibility - the information is conveyed mostly in digital text and unlike paper we don’t all have to experience that in the same way.
Some people can’t see the images in a website so we can add “alt” text which replaces the image for these people.
The problem comes when the image doesn’t actually have a meaning - then what should the Alternative text be?
There is a myth that the alt text should always say something.
In fact some images should have empty alt text - as this conveys the correct meaning - which is that the image is purely decorative and need not be considered to interpret the meaning of the page.
This is documented in the techniques and failures for web content accessibility guidelines document under “using null alt text and no title attribute on img elements for images that at should ignore”
If no title attribute is used, and the alt text is set to null (i.e. alt="") it indicates to assistive technology that the image can be safely ignored.