SharePoint 2010 Document Property Promotion and Demotion

The Case of the Missing Office Document Properties in SharePoint 2010

Nice article about  Document Property Promotion and Demotion

http://200oksolutions.blogspot.com/2013/08/property-promotion-and-demotion-in_21.html?showComment=1388156921931#c2368155112784597925

Property promotion is the functionality in WSS that pulls the document metadata (e.g. Title, Subject, etc) from Office 2003/2007/2010 documents during upload and sets those values to their corresponding column in WSS.  Property demotion is just the opposite, if you update the document properties (like Title) via the WSS UI that property value is written back to the file.  

Basically, with property promotion/demotion, we keep the properties in the document and in WSS in sync.

More info

http://msdn.microsoft.com/en-us/library/office/aa543341(v=office.14).aspx