What is a thru axle and how does it differ from a traditional quick release axle system?

A thru axle is a type of axle system used on bicycles that goes through the wheel hub and threads directly into the frame or fork. This provides a more secure and stiff connection compared to a traditional quick release axle system, which uses a lever to secure the wheel to the frame or fork. Thru axles are often used on mountain bikes and provide better stability and handling, especially in rough terrain.