An electricity market is a system that enables the exchange of electrical energy through an electrical grid. Historically, electricity has been primarily sold by companies that operate electric generators, purchased by electricity retailers, and sold to customers.
The electric power industry began in the late 19th and early 20th centuries in the United States and United Kingdom. Throughout the 20th century, and up to the present, many countries have made changes to their system of supplying and/or purchasing electricity. Change has been driven by many factors, ranging from technological advances (on both the supply and demand side) to politics and ideology.