Data transfer rate – the speed at which electronic data stored in one device travels to another device through some form of connectivity. It is measured in megabits or megabytes of data sent per second. When some data is transferred within one hard drive, it is called data transfer to disk, and the rate is expressed as megabits per second (Mbps). When data is sent from the buffer to the host party, it is expressed as megabytes per second (MBps).