You can think of it as a precursor to LDAP. It was a way to provide centralized access to User/Groups/Password and hostnames information over the network. YP w

You can think of it as a precursor to LDAP. It was a way to provide centralized access to User/Groups/Password and hostnames information over the network. YP was a staple of most UNIX deployments for some time, before being replaced by LDAP and DNS. You'll find some historical context here [1]. [1] https://en.wikipedia.org/wiki/Network_Information_Service https://en.wikipedia.org/wiki/Network_Information_Service