A client program is the software you use to connect to a server. If you have a SLIP, PPP or TCP/IP connection to the internet you can choose between many styles of programs for connection to the White Light game server.
Almost any telnet client program can be used to connect to the White Light game server. However, play is much easier with a dedicated MUD client program. Below is a list of program homepages for dedicated mud client or suitable telnet client software.