LDAP services exist in a TCP/IP context. It's an Internet service that uses daemons, requires an administrator, configuration files and structure. In some ways LDAP resembles a Linux file system with a root, limbs instead of directories, etc. Unlike the directory configuration of an operating system, LDAP is flexible in its structuring. That flexibility translates into a design makeup you can simply create. We call the hierarchical model a Directory Information Tree (DIT). Whoever designs the DIT needs to know something about how to model data.