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 Connecticut, 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 adhering to regulations and oversight by a governmental body. In Connecticut, the primary regulatory authority for public utilities is the Public Utilities Regulatory Authority (PURA), which operates under the Department of Energy and Environmental Protection (DEEP). PURA is responsible for ensuring that the state's utility companies provide safe, adequate, and reliable services at reasonable rates. The regulation of public utilities in Connecticut is governed by state statutes, which can be found in the Connecticut General Statutes, and by regulations outlined in the state's administrative code. Additionally, utilities that engage in interstate commerce or that are otherwise subject to federal jurisdiction may be regulated by federal agencies such as the Federal Energy Regulatory Commission (FERC).