@font-face…
…is a CSS method for specifying and embedding online fonts for display purpose. It is both a relatively new and old technology as it is supported in IE 6+ and recently in Safari 3.2+, Firefox 3.5+ and Chrome 4.0.2+ and has been long awaited by developers since its arrival in 1998. Technically it is not actually a font replacement technology but rather a CSS rule, however you can actually replace a font face (such as 'Arial') using this technique.