In general, information and attributes about users, objects, devices, applications, services, addresses or websites are collected and managed centrally in directory services. The term directory service( DS) is therefore used in a wide variety of technologies.
- InOSI terminology, directory services (DS) belong to the special application service elements( SASE). As a directory service, it is used to manage information about objects such as systems, peripheral devices, network components, files, users. It is often considered in connection with e-mail addresses, telephone numbers or certificates and provides functions such as searching and reading information in white pages or yellow pages. Provided by directory servers, examples of multi-vendor directory services include Cell Directory Service( CDS) and Global Directory Service( GDS) from OSF/ DCE, Domain NameSystem( DNS), Yellow Pages ( YP), and implementations of the international standard X.500. Directory Service is an ISO standard, ISO 9594, for converting host names and is used in TCP/ IP as a directory service in the Network Information Service( NIS). Examples of proprietary directory services are Active Directory Service( ADS) from Microsoft and NetWare Directory Service( NDS) from Novell. Specifically for searching e-mail addresses and domain names, there is the Internet service Whois and the registrars for domains, the Network Information Centers( NIC), and in Germany specifically Denic.
- The term Directory Service is also used in the context of Internet radios. Because Internet radio stations are no longer individual websites, they are also referred to as directory services in this context. One of these directory services is Shoutcast, which lists over 20,000 Internet radio stations; vTunes is another of many. There are also corresponding directory services for podcast services.