PCI Express, which is abbreviated officially with PCIe (PCI-E is also often used) and should not be mistaken for PCI-X, is an implementation of the PCI connection standard that uses existing PCI programming concepts, but bases it on a completely different and much faster full duplex, multi-lane, point to point serial physical-layer communications protocol. PCI Express was formerly known as Arapaho or 3GIO for 3rd Generation I/O.