Here is an example using css3:
CSS:
html, body {
height: 100%;
margin: 0;
}
#wrap {
padding: 10px;
min-height: -webkit-calc(100% - 100px); /* Chrome */
min-height: -moz-calc(100% - 100px); /* Firefox */
min-height: calc(100% - 100px); /* native */
}
.footer {
position: relative;
clear:both;
}
HTML:
<div id="wrap">
body content....
</div>
<footer class="footer">
footer content....
</footer>
Update
As @Martin pointed, the ´position: relative´ is not mandatory on the .footer element, the same for clear:both. These properties are only there as an example. So, the minimum css necessary to stick the footer on the bottom should be:
html, body {
height: 100%;
margin: 0;
}
#wrap {
min-height: -webkit-calc(100% - 100px); /* Chrome */
min-height: -moz-calc(100% - 100px); /* Firefox */
min-height: calc(100% - 100px); /* native */
}
Also, there is an excellent article at css-tricks showing different ways to do this: https://css-tricks.com/couple-takes-sticky-footer/