A dynamo is a device that converts mechanical energy into electrical energy using the principle of electromagnetic induction. It typically consists of a rotating coil of wire within a magnetic field, which generates electricity as the coil moves. Dynamos are commonly used in applications like bicycle lights and small generators. The invention of the dynamo is attributed to Michael Faraday, who discovered the basic principles of electromagnetic induction in the 1830s. Later, Hippolyte Pixii built the first practical dynamo in 1832. Dynamos played a crucial role in the development of electrical power systems before the advent of modern alternators.