A binary 0 might be represented by 0 volts of electricity (0 = 0 volts).

A binary 1 might be represented by +5 volts of electricity (1 = +5 volts).

Computers are designed to use groupings of eight bits. This grouping of eight bits is referred to as a byte. In a computer, one byte represents a single addressable storage location. These storage locations represent a value or single character of data, such as an ASCII code. The total number of combinations of the eight switches being turned on and off is 256. The value range of a byte is from 0 to 255. So a byte is an important concept to understand when working with computers and networks. 

Web Links Data Representations http://csep1.phy.ornl.gov/guidry/phys594/ lectures/performance_prog/data.html