[woofie]

so what happens if you dont put the dimensions in?

[Ex-Dem]

Putting in the dimensions reserves spaces for the images, so as soon as you load a page, it will be the correct height, even if the images aren't done loading yet. If you don't add the dimensions, then when you first load a page, it will be shorter than it should be, and when you start loading a particular image, the page height will grow to accommodate it, causing the jump effect. I'm not particularly bothered by it, but I guess some people would prefer no jumping.

[MaryFromMichigan]

so what happens if you dont put the dimensions in?

Not much.
Longer loading time.

[ForGod'sSake]

so what happens if you dont put the dimensions in?
I almost violated on of my own pet peeves here ;^)

A: DANCING THREADS

FGS