Digital in IT Glossary

Describes any system based on discontinuous data or events.
Computers are digital machines because at their most basic
level they can distinguish between just two values, 0 and 1,
or off and on. There is no simple way to represent all the
values in between, such as 0.25. All data that a computer
processes must be encoded digitally, as a series of zeroes and ones.
The opposite of digital is analog. A typical analog device
is a clock in which the hands move continuously around the face.
Such a clock is capable of indicating every possible time of day.
In contrast, a digital clock is capable of representing only a
finite number of times (every tenth of a second, for example).

In general, humans experience the world analogically. Vision,
for example, is an analog experience because we perceive infinitely
smooth gradations of shapes and colors. Most analog events, however,
can be simulated digitally. Photographs in newspapers, for instance,
consist of an array of dots that are either black or white. From afar,
the viewer does not see the dots (the digital form), but only lines
and shading, which appear to be continuous. Although digital
representations are approximations of analog events,
they are useful because they are relatively easy to store
and manipulate electronically. The trick is in converting
from analog to digital, and back again.

This is the principle behind compact discs (CDs). The music itself
exists in an analog form, as waves in the air, but these sounds are
then translated into a digital form that is encoded onto the disk.
When you play a compact disc, the CD player reads the digital data,
translates it back into its original analog form, and sends it to
the amplifier and eventually the speakers.

Internally, computers are digital because they consist of discrete
units called bits that are either on or off. But by combining many
bits in complex ways, computers simulate analog events. In one sense,
this is what computer science is all about.

Security in IT Glossary
In the computer industry, refers to techniques for ensuring that
data stored in a computer cannot be read or compromised by any
individuals without authorization. Most security measures involve
data encryption and passwords. Data encryption is the translation
of data into a form that is unintelligible without a deciphering
mechanism. A password is a secret word or phrase that gives a user
access to a particular program or system.