[Javascript] Image height and width

[Del Wegener]

Good Morning;
Normally the reference to an image on my web pages looks something like

<IMG src= ....../images_for_exercises/1_5_2a.gif" width=67 height=31 
align=absmiddle>

If I omit height and width I don't observe any change.

Is there a strong reason for including height and width?
Will my pages break if I stop including height and width?
What will go wrong?

Del