Hello, because this is a guild and like a guild, its made of people and players, so rules are the most important thing to sustain and keep the balance and respect.
First of all let's be moderated, if you can't handle a conversations/discussion you should just close your browser right now.
A guild is made of respect and friendship amongst their members, so a very important thing is to be respectfull and friendly.
This is the basics.
About internal guild rules, those will only be revealed once you are in.