In principle, when everybody understands and plays by the same rules, the experience is much more likely to be fun and rewarding than when people make up or assume their own rules and not everyone understands the protocol. Like playground rules posted on a fence, meeting ground rules encourage playing safely, having fun and including everyone. Group decision making is more efficient and achieves better results when we have shared expectations.
Practical Tip: Establish ground rules at the start of every meeting - such as with a simple list of 10 or fewer statements about how you all agree to behave in the meeting. The group might make a list from scratch or might discuss and revise a list proposed by the facilitator. Many groups use the same set of ground rules meeting after meeting. All participants should be watchful for compliance with the ground rules and politely point out violations. Review the ground rules regularly and do not hesitate to make additions or changes. Make sure new people understand the ground rules.