Briefly, OpenType is a font format jointly developed by Adobe and Microsoft in the late 1990ʼs. It came into wider use only after 2000, when Adobe included support for advanced typographic features in their InDesign, PhotoShop, and Illustrator applications. OpenType fonts support Unicode, which means that a single OpenType font can contain more than 65,000 glyphs. A single font can thus be used to set texts in various languages, such as English, Czech, Russian, Greek or Esperanto. OpenType fonts are cross-platform (i.e. the same file can be used on Mac and Windows computers), and OpenType fonts should behave consistently on both platforms.
Of course, not all OpenType fonts contain thousands of characters. In fact, most of the available OpenType fonts on the market are converted PostScript fonts containing only 256 glyphs. Typotheque offers Std and Pro fonts, with broad language support, eight different numeral styles, inferior and superior forms, case sensitive forms, arrows, pictograms, and more.
If you donʼt know what font format to choose, OpenType Std is a safe choice, as it work on both Mac and Windows platforms.