What category of adapter would you need to install to equip a system with one or more USB ports?

To equip a system with one or more USB ports, you would need a USB expansion card or adapter. These can be installed into a system's PCIe slot (for desktop computers) or connected via a USB port (for laptops or devices with limited expansion options). Options include USB 3.0, USB 3.1, or USB-C adapters, depending on the required specifications and compatibility with the system.