CardBus is a technology that allows laptops and other devices to use expansion cards for added functionality. It is an enhancement of the older PCMCIA standard, enabling faster data transfer rates and supporting 32-bit data paths. This makes it suitable for devices like network cards, modems, and storage solutions. Introduced in the mid-1990s, CardBus cards are typically inserted into a slot on the device, providing a way to upgrade or expand capabilities without needing to open the device. While it has largely been replaced by newer technologies like ExpressCard and USB, it played a significant role in the evolution of portable computing.