A public utility is an entity that provides the general public with essential goods and services such as electricity, natural gas, energy, water, sewer, heat, telecommunications (telephone, fiber optic or broadband internet), railroad, and rail transit.

Public utilities (goods and services) are often provided by a public utility corporation that is essentially given a monopoly over the provision of the good or service in a certain geographic area—and exemption from antitrust and unfair competition laws—in exchange for certain governmental restrictions and regulations. Public utility companies are often regulated by a governmental Public Utility Commission (PUC).

The laws and rules that govern public utilities are usually located in state or federal statutes—depending on whether the utility is regulated by the state or federal government. For example, many states have a public utilities code—sometimes called a public utility regulatory act—or provide for public utility corporations and their regulation in the state administrative code. The Federal Energy Regulatory Commission (FERC) is one example of a PUC at the federal level.

In Illinois, public utilities are regulated entities that provide essential services such as electricity, natural gas, water, and telecommunications to the public. These utilities are typically granted a monopoly within a certain geographic area in exchange for agreeing to be regulated by government entities. The primary state regulator for public utilities in Illinois is the Illinois Commerce Commission (ICC), which oversees and regulates the rates and services of public utilities to ensure that they are providing safe, reliable, and affordable services to consumers. The ICC also ensures that utilities comply with state laws and regulations. At the federal level, agencies like the Federal Energy Regulatory Commission (FERC) regulate aspects of utility services that cross state lines, such as electricity transmission and natural gas pipelines. State statutes, such as the Public Utilities Act (220 ILCS 5/), and administrative codes provide the legal framework for the regulation of public utilities in Illinois. These laws outline the responsibilities of public utilities and the ICC's authority in overseeing these entities to protect the interests of the public.