Bicycle dynamo is a small generator, usually in the front wheel's hub, that converts the wheel's spinning motion into electricity to power lights or charge devices, offering a reliable, self-sufficient alternative to batteries for cyclists, especially commuters and tourers. While technically often a magneto (producing AC), it's commonly called a dynamo, providing steady power (typically 3-6W) without stopping, though they add slight weight and drag, notes a YouTube video on dynamo hubs and BikeRadar.
Types of Dynamos
Hub Dynamo: Built into the front wheel hub, making it seamless and weather-resistant.
Bottle/Friction Dynamo: