Importing and Exporting Web Parts Using DWP Files
Microsoft® Windows® SharePoint™ Services uses XML documents with the .dwp extension as a way to import and export Web Parts so they can be shared by users. These files capture a snapshot of the property settings for a Web Part, and a reference to the assembly and class used to create it.
After the shared and personal properties for a Web Part are modified by using the task pane, you can capture the current state of the Web Part as a .dwp file by selecting Export from the Web Part menu. Importing that .dwp file creates a Web Part with the same state as the one that was exported. However, you can add elements to the .dwp file to specify additional property values, overriding the default property settings implemented in the Web Part code.
Note You can also use .dwp files to serialize and deserialize Web Part instances. This is especially useful when working with Web Parts such as the built-in Content Editor Web Part, which is a container for static HTML.
You can add a Web Part to a page, even if the Web Part is not yet included in a gallery, if you can locate a .dwp file for the Web Part, and if the assembly for the Web Part is available in the Global Assembly Cache (GAC) or in the bin directory for the virtual server. Most commonly, however, Web Parts are added to the page from one of the galleries. For more information about galleries, see Web Part Galleries.