OpenType is the newest, greatest font format designed by Adobe and Microsoft, designed to supplant TrueType and Type 1 - it's cross-platform, to facilitate compatibility between platforms.

OpenType is an evolution of TrueType Open, and thus contains some of its components, such as its advanced glyph substitution and layout features. It also has a sort of digital watermark designed to prevent modification of the fonts.

OpenType's file structure is just like TrueType Open's: a series of tables indexed by a table directory.

OpenType's compression technology depends on whether its font information is Type 1 or Truetype; for TrueType, it uses Agfa's lossless MicroType Express. Type 1 uses the "Compressed Font Format" by Adobe.