Sharepoint 2010 document information panel is a form that is displayed within the client application, and which contains fields for the document metadata. Document information panels enable users to enter important metadata about a file anytime they want, without having to leave the client application. For files stored in document libraries, the document information is actually the columns of the content type assigned to that file. The document information panel displays a field for each content type property, or column, the user can edit.

Users can edit document column values either at the document library level, or from within the Microsoft Office 2010 client application for the document. The metadata values are stored in the document itself, and in Microsoft SharePoint Foundation.Document information panels are available in Microsoft Word 2010, Microsoft PowerPoint 2010, and Microsoft Excel 2010.

How to Enable SharePoint 2010 Document Information Panel for a Document Library:
1.       Navigate to the Document Library for which the Document Information Panel needs to be enabled
2.       Click on Library Settings in the Library Tools Ribbon
3.       In the Library Settings page, click Document Content Type which is located under the Content Type Category
4.       Click on Documents Information Panel Settings under Settings
5.       Select the check box for “Always show Document Information Panel on document open and initial save for this content type”
6.       Click OK