A public utility is a company that maintains the infrastructure for a public service. Public utilities often involve natural monopolies, and as a result are often government monopolies, or if privately owned, treated as specially regulated sectors. Public utilities can be privately owned or publicly owned. Publicly owned utilities include cooperative and municipal utilities. Municipal utilities may actually include territories outside of city limits or may not even serve the entire city. Cooperative utilities are owned by the customers they serve. They are usually found in rural areas. Private utilities, also called investor owned utilities, are owned by investors. Unlike public companies, private utilities may be listed on the stock exchange. Private, in this context, means not owned by the public or the government.

In poorer developing countries, public utilities are often limited to wealthier parts of major cities, as used to be the case in developed countries in the nineteenth century.

Examples of utilities are:

• Electric Utility, which in some instances can be Electric power transmission or electricity distribution
• Drinking water purification and distribution
• Sewage treatment and disposal
• Other waste disposal
• Natural gas distribution
• District heat generation and distribution
• Public transport by bus, train, etc.
• Cable television and telephone lines