PCI Express (Peripheral Component Interconnect Express) is a high-speed serial computer expansion bus standar.
It is the common motherboard interface for personal computers’ graphics cards, capture cards, sound cards, hard disk drive host adapters, SSDs, Wi-Fi, and Ethernet hardware connections.
PCIe has numerous improvements over the older standards, including higher maximum system bus throughput, lower I/O pin count and smaller physical footprint, better performance scaling for bus devices, a more detailed error detection and reporting mechanism and native hot-swap functionality. More recent revisions of the PCIe standard provide hardware support for I/O virtualization.
The PCI Express electrical interface is measured by the number of simultaneous lanes. A lane is a single send/receive line of data, analogous to a “one-lane road” having one lane of traffic in both directions.
Source: Wikipedia