Microsoft applications like "Word" or "Excel" let the user describe his document by properties like "title", "category" and so on. The application itself adds further information: last author, creation date etc. These properties are stored in so-called property set streams. A property set stream is a separate document within a POI filesystem. HPSF is POI's pure-Java implementation to read (and in future to write) property set streams.

The HPSF HOWTO describes what a Java application should do to read a property set using HPSF and to retrieve the information it needs.

HPSF supports OLE2 property set streams in general, not only the special case of document properties mentioned above. The HPSF description describes the internal structure of property set streams.