There are multiple file formats for digital fonts. Each one is specifically designed for optimal use at different times and situations.

HISTORY

The history of digital fonts includes several major formats. The most notable ones are:
• PostScript Type 1, developed by Adobe in 1984;
• TrueType, developed by Apple in 1991;
• Multiple Master Type 1, Adobe, 1992;
• TrueType GX, Apple, 1994;
• OpenType, co-developed by Microsoft and Adobe in 1996.

GOING FURTHER

Today, OpenType is the dominant format in use (extension name as .otf). It supports both PostScript and TrueType outline technologies, which now exist as two flavors or outlining models within the OpenType container.
WOFF and WOFF2 are additional web-optimized containers that compress and package OpenType/TrueType fonts for efficient delivery over the internet. The term format tends to be used instead of flavor but, technically, PostScript and TrueType are no longer standalone formats; instead, they are integrated into the broader and more versatile OpenType ecosystem.