~ Computer logic

~ Binary

Binary is a number system. It is the ideal number system to represent two-states because it has only two digits : 0 and 1

~ ASCII

ASCII ( American Standard Code for Information Interchange ) is an 8-bit code used to represent characters in binary.
                                                           8-bits = 256 characters 

~ Unicode

An international organisation, known as the Unicode Consortium, was formed to deal with the problems that the ASCII had.
                                                       16-bit = 65,539 characters 


~ Modem

Convert between the analogue signals used in telephone cables and the digital signals used by a computer.