765 ILCS 735/1.1
As used in this Act:
"Agreement" includes leases, oral agreements, and any other understandings or contracts reached between a landlord and a tenant.
"Individually metered utilities" means that the utility service to one or more rental dwelling units in a building is registered by an individual meter for each dwelling unit.
"Master metered utilities" means that the utility service to a building with one or more rental dwelling units is registered by a single meter for the building.
"Landlord" includes the owner of a building, the owner's agent, and the lessor of a building.
"Tenant" includes occupants of a building or mobile home, whether under a lease or periodic tenancy.
"Utility company" includes all suppliers of utility service, including municipalities.
"Utility service" includes electric, gas, water, or sanitary utility service rendered by a utility company to a tenant at a specific location.
765 ILCS 735/1.1