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Computer science from A to Z

K is for Kilobit

© INRIA Sophie Auvin - K comme Kilobit

The quantity of information that a network can transmit increases by a factor of nearly 1000 every 10 years:

from several thousand bits (kilobits) per second in 1980, to a few million (megabits) in 1990, to billions (gigabits) in the 21st century.

This progression is impressive... but it is never sufficient, because insatiable Internet users are exchanging more and more data all the time! After short written messages came exchanges of baby photos and teenagers' favourite songs. Today, we have telephone and video; will tomorrow see 3D virtual objects?

In order to avoid network saturation, we are always trying to compress information more, to express more in fewer bits. Often, images or sound have declined in quality by the time they arrive.

And how can we reduce the size of files that must not be altered, such as texts or software? There exist “no-loss ” methods, which operate at a lower compression rate but are totally reversible.

Did you know...?

© INRIA / Sophie Chauvin - Kilobit

By identifying frequently recurring data in a document in order to “code ” them more concisely, we can easily reduce their size by a factor of three.
By deleting from an image the details that the naked eye cannot see, we can easily reduce its size by a factor of ten or more.

Keywords: Computer science from A to Z Science awareness

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