Definition - What does Quorum mean?
A quorum is the quota for the minimum amount of group members that are required to be present at a meeting for a decision to go through.
In the context of the law, quorums are often required for groups to make legally binding decisions. Groups who may require quorums are government agencies, company boards, etc.
Justipedia explains Quorum
If quorums were not required, then a single person or a very small group of people could make decisions on behalf of an entire group. This could present problems. For example, if a single senator could make decisions on behalf of the entire Senate, then it would defeat the purpose of the Senate, which is to represent the states of the country evenly.
Decisions that are made without a quorum when a quorum is needed may not be legally binding or enforceable.