A secondary winding is a coil of wire in a transformer that receives electrical energy from the primary winding. It is responsible for producing an output voltage that can be higher or lower than the input voltage, depending on the turns ratio between the primary and secondary windings. This process is essential for transferring electrical energy efficiently in various applications. In a typical transformer, the primary winding is connected to the power source, while the secondary winding connects to the load. The interaction between the two windings allows for the conversion of voltage levels, making transformers crucial in power distribution systems and devices like power adapters and electrical transformers.