The most common example of the information provided is user account names for user IDs. For example, when a user runs ls, the files listed only have a UID number stored on the filesystem.
name service turns that number into a user name, by looking at the sources (such as a local passwd file, or ldap) configured in nsswitch.conf
Name service is a separate task than authentication, which is handled by PAM on most Unix systems. The two are frequently confused with each other, as systems which provide user account information also store credentials used to authenticate.
Name service is primarily concerned with account data, whereas PAM handles authentication and authorization.
Patent No. 7,733,851 Issued on June 8, Assigned to IDIS for Name Service System, Method (South Korean Inventors)
Jun 09, 2010; ALEXANDRIA, Va., June 15 -- Sung-Bok Kwon, Dae-Won Kim and Sang-Hoon Lee, all from Seoul, South Korea, have developed a name...
Patent No. 7,593,968 Issued on Sept. 22, Assigned to Silicon Graphics for Distributed Name Service Relocation Method (California Inventor)
Sep 22, 2009; ALEXANDRIA, Va., Sept. 22 -- Ken Beck, Morgan Hill, Calif., has developed a method of relocation of a distributed name service in...