Although WOFF and WOFF2 have become the predominant formats, we still ship EOTs so that no Internet Explorer 6 gets left behind. Not all browsers accept the same format, so that’s why you’ll get three. They are:
EOT, Embedded OpenType — compatible with Internet Explorer 6+.
WOFF, Web Open Font Format — compatible with Firefox 3.6+, Safari 5.1+, Chrome 5+, Internet Explorer 9+, Opera 11.5+, Android 4.4+, and iOS Safari 5.1+.
WOFF2 — The next-generation of WOFF providing a compression advantage of roughly 20–30% off the font’s file size. Compatible with Firefox 3.6+, Safari 5.1+, Chrome 36+, Edge 14+, Opera 23+, Android 67+, and iOS Safari 10+ (Mac OS Sierra and up only).
Visit Can I use… for further details about browser support for each format.