A Web Part Gallery is an organized central library of Web Parts that you can use to locate a specific Web Part to add to your Web Part page. You can access Web Part galleries when you are in Edit mode in your Web Part page by selecting Browse from the Add Web Parts menu of the Web Parts tool pane. See the “Adding a Web Part to a Web Part page” section earlier in this chapter.
Web Part galleries are actually lists of installed Web Part Definition (.dwp file extension) and Web Part (.Web Part file extension) files. Depending on how your site administrator has configured your site, there are typically three or four Web Part galleries:
Closed Web Parts: Contains Web Parts assigned to the page but not visible.
Site Gallery: Contains Web Parts that a server administrator has decided are safe and are therefore available to all sites in a collection. The name of this gallery is the name of the collection’s top-level Windows SharePoint Services Web site.
Server Gallery: Contains Web Parts that a server administrator has made available to all site collections (sites and sub-sites) on a single virtual server.
Online Gallery: Contains Web Parts available from Microsoft or other third-party software vendors. By default, the Online Gallery contains an additional set of Web Parts available from Microsoft. However, a site administrator can redirect the online library to a different site.
The following Web Parts are available in both ...