The Illinois Open Meetings Act covers all “public bodies.” The term “public body” includes
all legislative, executive, administrative or advisory bodies of the State, counties, townships, cities, villages, incorporated towns, school districts and all other municipal corporations, boards, bureaus, committees or commissions of this State, and any subsidiary bodies of any of the foregoing including but not limited to committees and subcommittees which are supported in whole or in part by tax revenue, or which expend tax revenue, except the General Assembly and committees or commissions thereof.