This term usually refers to the person behind the wheel of a moving car. In the computer world, however, a driver is a small file that helps the computer communicate with a certain hardware device. It contains information the computer needs to recognize and control the device. In Windows-based PCs, a driver is often packaged as a dynamic link library, or .dll file. In Macs, most hardware devices don't need drivers, but the ones that do usually come with a software driver in the form of a system extension, or .kext file.