Have you ever needed to use a USB port, but they were all occupied? Or, worse, you needed to connect to your computer via other devices but your motherboard or notebook just couldn't. It is in situations like these that you will really appreciate the functionality of a controller.
Controllers are used to extend port equipment and computers, and come in several forms. These include internal controller cards in desktop computers, cards in the expansion slot of your notebook, and additional USB devices. Purchasing a suitable controller can easily prevent having to buy a new expensive motherboard, notebook or desktop computer.