Thunderbolt (codenamed Light Peak) is a hardware interface that allows for the connection of external peripherals to a computer. It uses the same connector as Mini DisplayPort (MDP). It was released in its finished state on February 24, 2011. Thunderbolt combines PCI Express (PCIe) and DisplayPort (DP) into one serial signal alongside a DC connection for electric power, transmitted over one cable. Up to seven peripherals may be supported by one connector through various topologies.