I just stumbled across [this question](https://stackoverflow.com/questions/3451541/css-font-face-anti-aliasing) and I noticed the user is using some notation I've never seen before:

```css
@font-face {
   /* CSS HERE */
}

```

So is this `@` symbol something new in CSS3, or something old that I've somehow overlooked? Is this something like where with an ID you use `#`, and with a class you use `.`? Google didn't give me any good articles related to this. What is the purpose of the `@` symbol in CSS?