Background-size:cover and background-size:contain were designed for one purpose — to make life easier when working with background images. And you know what? They do!
Unfortunately, some projects still require Internet Explorer 8 support, which does NOT like the background-size property.
Luckily, that’s where this awesome polyfill comes in!
Simply implement a bit of CSS linking to a /backgroundsize.min.htc, and then modify your htaccess (for Apache [adds mimetype for htc]) and you’re ready to go.
Very easy. Very useful.