One of the main reasons for using a content management system like SharePoint is to efficiently find the right documents and to enforce well-defined processes that govern documents' behavior during different stages of their life cycle. Both of these activities would greatly benefit from the use of metadata, especially if the metadata model is properly designed and the values are consistently applied to documents.
Metadata typically contains several names/value pairs called attributes that describe a particular document. For example, an attribute name could be "Keywords" and the values could be specific keywords associated with certain documents like a web page or MS Word file. In more complex examples, metadata may have tens of attributes specifying different aspects of the document origin or use, such as Vendor, Country, Information Category, Source, Retention Policy, Archival Date, etc.
|How to Use SharePoint Metadata to Improve Search and Control Content|