Bits and Bytes

A Bit is a single piece of digital information. A Bit can only be one of two states “on” or “off” therefor a single bit can hold only 1 piece of information. To hold more information, bits are combined in groups. A Byte is a group of 8 Bits. Such a group can hold 256 distinct pieces of information.  If more information is required then it can be represented by two or more bytes.

When determining the size of a file, it is standard practiced to express this by the number of bytes occupied by the file. As file sizes become larger, metric units have been used to express this more easily as follows:

When measuring the speed of a network connection, it is standard practice to represent this as a number of bits (not bytes) transmitted per second.

Note that if you were to send a  1 MByte file (1,000,000 bytes = 8,000,000 bits) down a network connection that worked at a transmission speed of 1 Mbps (1,000,000 bits per second) you might reasonably expect it to take 8 seconds to transmit the file. In practice this is not the case because the network connection will add extra bits to the transmission in order to setup and maintain communications on the network. These bits effectively increase the amount of information being transferred.