"A directory service is a physically distributed, logically centralized
repository of infrequently changing data that is used to manage a
computing environment."
Not a new concept (Grapevine, StreetTalk), but a widespread
urgent problem today.
System management is:
maintaining and distributing structured, consistent data
about managed objects:
systems, services, accounts, groups, permissions,
...
maintaining and expressing relationships between entities
LDAP provides:
vendor-neutral relatively lightweight secure protocol;
schema definition, occasionally standard;
managed hierarchical (local) object space;
standalone deployment model, with referrals;