Sound and Silence
Alt attributes
Close up photo of the human iris. From Wickipedia, the iris is is a thin, annular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina. Eye color is defined by that of the iris. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm. This iris has an outer edge that is cool as water, and the inner ring is like grass on fire. A classic style camera sits on a bed of hand sized, smooth rocks. The camera's shutter works like the eye's retina and iris.  The lens helps transfer the image, and as the shutters open to let light in to be captured, the film inside is exposed to the light rays which give us the 2 dimensional layout of the object in color, or black and white depending on the film. A photo, view from above, of a table where a laptop, a pair of noise canceling headphones and a camera sit. Screenreaders use alt image attributes to read to the user what the image is, it's description, or perhaps the story it tells.

They say a picture is worth a thousand words, but imagine if there was no image.
Now what story are we trying to tell?
Screen readers help those with visual difficulties interact with the images on a page. If the image is important to the page, an alt attributes should be in the image tag to allow the reader to tell the user what is being depicted in the image or what message is being relayed in the image. While some images are just for design and decoration, if an image tells a story, don't leave anyone out, and include this story in the page for all to view by using that alt attribute.
Click on the buttons above the images to hear the alt attributes.