In Score Guild Ranks are displayed along with the guild they belong.

A person can belong to up to 5 guilds simultaneously and in each assigned a different rank, reputation and salary.

You can find out about the different guilds by using the Guilds command to see the different guilds and their leaders.

If you would like to join a guild you need to speak to a guild leader or, in the case of inactive guild leaders, speak with an immortal about joining that guild.