What is the difference between * scaling and scaling?

Question

in the reset part of the boot file there is

.clearfix {
*zoom: 1;
}

May I ask what is the difference between * scaling and scaling?

I appreciate any answer.

Answer 1

it is a css hack, which means that it only applies to ie7 and below. You can get detailed information here: http://www.webdevout.net/css-hacks#unrecommended-asterisk_prefix

Answer 2

http://en.wikipedia.org/wiki/CSS_filter#Star_hack

I think that it is necessary to fix IE here.