Adobe Font Folio is a collection of over 2300 OpenType fonts. An OpenType font is a cross-platform font file format, co-developed by Adobe Systems and Microsoft. Font Folio is a collection of fonts designed by several renowned type foundries. As of early 2005, there were around 10,000 fonts available in OpenType format. Adobe's library makes up under a third of the total, all of which are included in Font Folio.