Font File Formats
Font files are the most quietly important format category on the internet — every word you're reading right now was delivered as one.
Formats 10
Most common .afm, .dfont, .eot
Font files are the most quietly important format category on the internet. Every word you're reading right now was delivered as a font file. The web moved from system fonts to custom web fonts to variable fonts in about fifteen years, and the file formats evolved with it — from TrueType to OpenType to WOFF to WOFF2.
For desktop use, TTF and OTF are the formats you install — double-click the file, click "Install," and your apps can use the font. OTF is the more modern format with advanced typographic features (ligatures, alternates, small caps). For web use, WOFF2 is the only format you should be serving — it's the same font data compressed with Brotli for faster loading.
The format you need depends on where the font is going. Designing for print? OTF. Building a website? WOFF2. Distributing a font that needs to work everywhere? Include both OTF (for desktop) and WOFF2 (for web). EOT is dead — it was Microsoft's format for Internet Explorer, and both have been put out to pasture.
What's the difference between TTF and OTF?
Both work everywhere. OTF supports advanced typographic features (ligatures, stylistic alternates, variable weights) and uses smoother cubic curves. TTF is older but equally compatible. For most users, the difference is invisible. For designers, OTF is preferred.
What font format should I use for my website?
WOFF2. It's the current standard — supported by every modern browser, compressed with Brotli for fast loading. Include a WOFF fallback for very old browsers if you must, but WOFF2 alone covers 97%+ of web traffic.
How do I install a font?
On any OS, double-click the .ttf or .otf file and click Install. On macOS, Font Book manages installed fonts. On Windows, the font appears in Settings → Personalisation → Fonts. Restart applications to see newly installed fonts.