Digital typography has undergone a remarkable evolution since the first bitmap fonts of the 1960s, and the proliferation of font formats reflects the diverse technical requirements of different platforms, rendering engines, and distribution models. Understanding these formats is essential for anyone working with type in digital environments.

TrueType (TTF) was developed jointly by Apple and Microsoft in the late 1980s as an alternative to Adobe's proprietary PostScript fonts. TrueType rendered fonts on screen using a sophisticated hinting system with a stack-based programming language that gave type designers precise control over how glyphs appeared at small sizes on low-resolution displays. TrueType fonts store glyph outlines as quadratic Bézier curves, which are computationally simpler but require more control points than the cubic Bézier curves used by PostScript. The format was bundled with both Mac OS and Windows, ensuring universal desktop compatibility that persists to this day.

OpenType (OTF) was introduced in 1996 as a collaboration between Microsoft and Adobe to unify TrueType and PostScript font technologies under a single specification. OpenType fonts can contain either TrueType (quadratic) or PostScript (cubic, CFF) outlines. The format's most significant advancement was its layout engine, which supports advanced typographic features like ligatures, contextual alternates, stylistic sets, small caps, old-style figures, and complex script shaping for languages like Arabic, Devanagari, and Thai. An OpenType font can contain over 65,000 glyphs, compared to TrueType's practical limit of a few hundred, enabling comprehensive Unicode coverage and extensive alternate character sets.

The Web Open Font Format (WOFF) was developed specifically for web use and became a W3C Recommendation in 2012. WOFF is essentially a wrapper around TrueType or OpenType fonts with added compression (using zlib) and metadata fields. The compression typically reduces font file sizes by 40–50% compared to raw TTF or OTF files. WOFF also includes provisions for font licensing metadata, addressing the intellectual property concerns that initially made font foundries reluctant to allow their fonts on the web.

WOFF2, published as a W3C Recommendation in 2018, uses the Brotli compression algorithm instead of zlib, achieving significantly better compression ratios—typically 30% smaller than WOFF and 50–70% smaller than the original TTF or OTF file. Brotli was developed by Google specifically for web content compression and excels at compressing font data. WOFF2 is now supported by all major browsers and is the recommended format for web fonts, as smaller file sizes directly translate to faster page loads and improved user experience. The CSS @font-face rule enables web developers to specify multiple font formats with fallbacks, loading WOFF2 when supported and falling back to WOFF or TTF for older environments.

Variable fonts, introduced in OpenType 1.8, represent the most significant recent advancement in font technology. A single variable font file can contain an entire family of weights, widths, slants, and custom axes of variation, replacing what previously required dozens of separate font files. This dramatically reduces the total download size for web projects that use multiple weights of a typeface and enables smooth, continuous transitions between styles that were previously impossible.