Webfont licenses allow your font to live on your website using the CSS @font-face rule and come in two formats; EOT and WOFF.
Internet Explorer uses EOT, Embedded OpenType, to render webfonts and it has been supported since version 4.0. While WOFF, Web Open Font Format, is supported by multiple browsers — and it is currently in the process of being standardized upon the recommendation of the W3C.
If you are new to webfonts then take a peek at FontShop’s Designers Guide to Webfonts, available on our education page. It’s great introduction and while you’re there you can brush up on your typography skills.
We also recommend downloading FontFont’s webfont user guide, available here, for more in-depth reading aimed at web developers and system administrators.