When listing the HTML dimension attributes belonging to tags such as
<video>, we have the option of including
height, and vice versa. For example:
<video width="320" height="240">
which is the equivalent to
<video height="240" width="320">
<img src="shihtzu.jpg" width="50" height="50" alt="">
which is equal to
<img src="shihtzu.jpg" height="50" width="50" alt="">
The convention, however, is to list
height. Browsers do it. Image previewers do it.
In Firefox, for example, if you hover your mouse over an image and perform a context-click (right-click for right handers), choose View Image…
then hover your mouse over the title tab, you’ll see the image’s width listed before its height.
And, lastly, in Windows 8.1, if you view an image in Windows Photo Viewer and bring up the Properties panel (Alt + Enter), then click the Details tab, you’ll see the image’s width listed before height under the Image heading.
Hope I’ve convinced you.