Font embedding refers to technology that saves fonts (or subsets of fonts) inside document files. The aim of this is that recipients of the document can see it as it was designed, without having to have the fonts already installed on their computer. The benefits for publishers are obvious.
Restrictions on embedding
For many years it has concerned type designers and foundries that font embedding entails their data moving, inside documents, to places where it is not licensed. It has not been possible to assure foundries that font data is not extractable from documents containing embedded fonts.
Around 1991 Microsoft extended the TrueType specification to allow font developers to specify under what conditions their fonts may be embedded inside documents. At that time, before the web and mass use of e-mail, it was probably thought that documents would not often travel widely. Thus the first form of the specification does not offer much control to font developers. For more, see embedding bits.