CSS question, what does url do?

[newkid]

This is from a Site I now have to maintain. In the code below what does or what is this for, the url porttion on the import and backgroud images? I have never seen it used before and could not find any thing on it.

@import url("assets/fp.css");
#corral {
	height: 463px;
	width: 319px;
	position: absolute;
	left: 55px;
	top: 0px;
}
#leftlines {
	background-image: url(assets/hm_stripe_bg.gif);
	background-repeat: repeat-y;
	position: absolute;
	height: 463px;
	width: 55px;
	left: 0px;
	top: 0px;
}
#mainblock {
	background-image: url(assets/hm_grad_bg.gif);
	background-repeat: repeat-x;
	position: absolute;
	height: 522px;
	width: 100%;
	left: 0px;
	top: 78px;
}

Thanks
J.C.
To learn is a good thing and today I hope to learn somthing new!

[gohankid77]

It acts like the "src" attribute of an <img/> tag in that it specifies where the CSS file and background image are located.