Font embedding
Font embedding refers to the ability to embed font files into a document. This has been a feature of Microsoft Word for Windows and some other applications for many years. It is controversial because it can potentially allow copyrighted fonts to be freely distributed.
Font embedding in word processors
Microsoft Word for Windows has permitted font embedding since Word 97.
Font embedding on the Web
Currently, Internet Explorer, Firefox, Safari, and Opera 10 beta support font embedding.
Controversy
The controversy can be mitigated by only embedding the characters required to view the document, but this necessarily prohibits addition of previously unused characters to the document.
Because of the potential for copyright infringement, Internet Explorer only permits embedded fonts that include digital rights management (DRM) protections. The Acid3 test requires font embedding with minimal DRM protections.