known as the Third Industrial Revolution, is the change from analog, mechanical, and electronic technology to digital technology which began anywhere from the late 1950s to the late 1970s with the adoption and proliferation of digital computers and digital record keeping that continues to the present day.

1980Cell phone subscribers: 11.2 million Internet users: All Internet users at this

time were indexed in a phone book sized directory.

1990Cell phone subscribers: 12.5 million

(0.25% of world population in 1990)Internet users: 2.8 million (0.05% of

world population in 1990)

2002Cell phone subscribers: 1.2 billion (19%

of world population in 2002)Internet users: 631 million (11% of world

population in 2002)

2010Cell phone subscribers: 4 billion (67% of

world population in 2010) Internet users: 1.8 billion (26.6% of world

population in 2010)

The underlying technology was invented in the later half of the 19th century, including Babbage's analytical engine and the telegraph. Digital communication became economical for widespread adoption after the invention of the personal computer. 

Claude Shannon, a Bell Labs mathematician, is credited for having laid out the foundations of digitalization in his pioneering 1948 article, A Mathematical Theory of Communication.[7] The digital revolution converted technology that previously was analog into a digital format. By doing this, it became possible to make copies that were identical to the original.

Computer generally means a programmable machine. The two principal characteristics of a computer are: it responds to a specific set of instructions in a well-defined manner and it can execute a prerecorded list of instructions (a program).

Modern computers are electronic and digital. The actual machinery — wires, transistors, and circuits — is called hardware; the instructions and data are called software.

Chapter 1 Computer Systems

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Babbage’s Analytical Engine

ENIAC