PCIe

PCIe (Peripheral Component Interconnected Express) is a protocol for connecting high-speed components that comes in multiple physical configurations for different data transfer speeds. These configurations are defined by the number of transfer lanes ranging from 1-32. They each correspond to different generations as seen below:

These slots are backwards compatible with slower PCIe cards. Notice that the bandwidth (ie. maximum data transfer rate) doubles with each generation. The gigatransfer refers to the rate of transfers per second. This does not specify the amount of data per transfer. The frequency refers to the clock/oscillator frequency that the protocol operates on.