This policy setting allows you to add a specific set of search providers to the user's default search provider list. Normally, ...

This policy setting allows you to add a specific set of search providers to the user's default search provider list. Normally, search providers can be added from third-party toolbars or in Setup, but can also be added by the user from a search provider's Web site.

If you enable this policy setting, users can add and remove search providers, but only from the set of search providers specified in the list of search provider policy keys (found under [HKCU or HKLM\Software\policies\Microsoft\Internet Explorer\SearchScopes]). Note: This list can be created using a custom administrative template file. For information on creating this custom administrative template file, see the Internet Explorer documentation on search providers. 

If you disable or do not configure this policy setting, the user will be able to configure their search provider list unless there is another policy setting restricting such configuration.