Why we need add a auto value to the height property?

[foadmosba]

in this practice i dont understand why we must add

height: auto
to the CSS of images, even without it the image still responsive well and the fully show in different screens?

and also in don’t understand the use of
display: block;
for it (thats rule also was not create any change)

[mtf]

The height is automatically scaled to be proportional to the width. We cannot set height and width on inline elements (img is inline) so converting it to a block level element clears the way for those properties.