The site user search lets you search for site groups and users using a range of filters.
The iCM search indexes a user's preferred name, email address, the login usernames linked to their account, and any field set as "searchable" in your site's userprofile object. If you change the searchable settings of any fields in the userprofile object, you'll need to reindex your site user search collection for the changes to be reflected in the search results.
Searches are case insensitive and return any results that have words containing the text you search on. So searching for Fred would return Fred, Alfred and Freddie.
Note that only account users are returned in the search. Login users names are indexed, and cause the account user they are associated with the to appear in the results.
Use an asterisk to perform wildcard searches.
Searching on * will return all groups and users that match your chosen filters, although there is a limit of 20,000 results.
You can also use an asterisk to perform stemming. So Fred* would return Fred and Freddie, but not Alfred. Conversely *fred would only return Fred and Alfred.
Filters are enabled by checking the various checkboxes on the search homepage.
The two top-level filters let you search for users, groups, or both.
The login provider filter lists all of the providers currently defined in the configuration of the Authentication worker. To search for all users that have a particular provider, check the box next to that provider's name. You can also search for users that don't have any login accounts (which may happen immediately after an upgrade, or if someone has manually created users in iCM) or any users that have providers that are not currently configured (this would only occur if you removed a provider that had previously been in use).