It is measured in bits per second "and is used to express the speed at which they transmit or process the data. A higher bit rate, the more data processed and therefore higher image resolution. The formats of digital video is usually measured in megabits per second (Mbps). (One megabit equals one million bits). The maximum bit rate for DVD is 10 Mbps; for HDTV is 19.4 Mbps.

The bits are pieces of each word, which is called a sample. Contraction of "binary digit," the smallest unit in computer data handling (either a zero or a one) equal to one binary decision. In a CD player, there are 44,100 16-bit samples of the audio per second, and there are two streams for stereophonic playback. This makes for a 'sampling rate' that is called 'stereo 16-bit 44.1 kHz' (k = 1000, Hz = cycles per second.)

Generally speaking, a low bit rate means lower sound quality and a smaller file size, while a high bit rate means better quality and larger files. However, compression algorithms vary. For instance, a 96Kbps (kilobits per second) MP3 Pro file may sound better than a 160Kbps MP3 file, or a 1Mbps (megabits per second) DivX file may look better than a 2Mbps MPEG-1 file.