ABSTRACT
Suppose you want to send an e-mail message to a friend. Your message may be an ordinary string of English words, but your computer can only send electronic messages. So a program is used to convert your words into a string of instances of two states, “power on” and “power off.” For our convenience let’s write 1 for “power on” and 0 for “power off”; your message no longer looks like “Let’s meet for lunch,” but something like 100110110011000011011100010110011011100010110011011001001011000 . https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315366890/f4bfe916-bec8-4e54-8a5a-ffef17c80cb7/content/eq641.tif"/>
