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 California, public utilities are regulated entities that provide essential services such as electricity, water, and telecommunications to the public. These utilities are typically granted a monopoly within a certain geographic area in exchange for agreeing to governmental oversight and regulation. The primary regulatory body in California is the California Public Utilities Commission (CPUC), which oversees the rates, operations, and services of these utilities. The CPUC ensures that Californian consumers have access to services that are safe, reliable, and reasonably priced while also considering environmental impacts. The regulation of public utilities in California is governed by the California Public Utilities Code, which sets forth the laws pertaining to the control and regulation of public utilities within the state. Additionally, federal regulation, such as that by the Federal Energy Regulatory Commission (FERC), applies to utilities that operate across state lines or that are involved in the wholesale electricity market, natural gas transmission, or the interstate transportation of oil by pipeline.