Fast infoset specifies a standardized binary encoding for the xml information set. an xml infoset (such as a dom tree, stax events or sax events in programmatic representations) may be serialized to an xml 1.x document or, as specified by the fast infoset standard, may be serialized to a fast infoset document.

fast infoset documents are generally smaller in size and faster to parse and serialize than equivalent xml documents.