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# Computer science

## 1.

Computer scienceComputer science is the study of the theoretical

foundations of information and computation and how

they can be implemented in computer systems.[1][2][3] It is

a broad discipline, with many fields. For example,

computer programming involves the use of specific

programming languages to craft solutions to concrete

computational problems. Computer graphics relies on

algorithms that help generate and alter visual images

synthetically. Computability theory helps us understand

what may or may not be computed, using current

computers. On a fundamental level, computer science

enables us to communicate with a machine, allowing us to

translate our thoughts and ideas into machine language, to

give instructions that the machine can follow, and to

obtain the types of responses we desire.

## 2.

Computer science has touched practically every aspect of modernday life. For instance, it has led to the invention of general-purposecomputers, for tasks ranging from routine writing and computing to

specialized decision making. It has led to the development of the

Internet, search engines, e-mail, instant messaging, and e-commerce,

bringing about a revolution in our ability to access and

communicate information and to conduct financial transactions. By

enabling the development of computer graphics and sound systems,

it has led to new ways of creating slides, videos, and films. These, in

turn, have given birth to new approaches for teaching and learning.

For research in various fields, computer science has greatly

enhanced the processes of data gathering, storage, and analysis,

including the creation of computer models. By fostering the

development of computer chips, it has aided in the control of such

things as mobile phones, home appliances, security alarms, heating

and cooling systems, and space shuttles. In medicine, it has led to

the creation of new diagnostic and therapeutic approaches. For

national defense, it has led to the development of precision

weaponry.

## 3.

Through the development of robots, it has enabled theautomation of industrial processes and helped in such

tasks as defusing bombs, exploring uncharted territories,

and finding disaster victims.

On the down side, knowledge of computer science can

also be misused, such as in creating computer viruses,

computer hacking, and "phishing" for private

information. These activities can lead to huge economic

losses, theft of identity and confidential information, and

breach of national security. In addition, the fruits of

computer science—particularly the Internet and its

associated forms of communication—can be used to

spread falsehoods, motivate immoral or unethical

behavior, or promote acts of terrorism and war. Such

misuse can create enormous problems for society.

## 4.

HistoryThe earliest known tool for computation was the abacus, thought

to have been invented in Babylon around 2400 B.C.E. Its original

style of usage was by lines drawn in sand with pebbles. In the fifth

century B.C.E., Indian grammarian Pāṇini formulated sophisticated

rules of grammar for Sanskrit. His work became the forerunner to

modern formal language theory and a precursor to computing.

Between 200 B.C.E. and 400 C.E., Jaina mathematicians in India

invented the logarithm. Much later, in the early sixteenth century,

John Napier discovered logarithms for computational purposes, and

that was followed by the invention of various calculating tools.

None of the early computational devices were computers in the

modern sense. It took considerable advances in mathematics and

theory before the first modern computers could be designed.

Charles Babbage, called the "father of computing," described the

first programmable device—the "analytical engine"—in 1837, more

than a century before the first computers were built. His engine,

although never successfully constructed, was designed to be

programmed—the key feature that set it apart from all preceding

devices.

## 5.

Prior to the 1920s, the term computer was used inreferring to a human clerk who performed

calculations, usually led by a physicist. Thousands of

these clerks, mostly women with a degree in calculus,

were employed in commerce, government, and

research establishments. After the 1920s, the

expression computing machine was applied to any

machine that performed the work of a human

computer—especially work that involved following a

list of mathematical instructions repetitively.

Kurt Gödel, Alonzo Church, and Alan Turing were

among the early researchers in the field that came to

be called computer science. In 1931, Gödel

introduced his "incompleteness theorem," showing

that there are limits to what can be proved and

disproved within a formal system. Later, Gödel and

others defined and described these formal systems.

## 6.

In 1936, Turing and Church introduced the formalization of analgorithm (set of mathematical instructions), with limits on what

can be computed, and a "purely mechanical" model for computing.

These topics are covered by what is now called the Church–Turing

thesis, which claims that any calculation that is possible can be

performed by an algorithm running on a mechanical calculation

device (such as an electronic computer), if sufficient time and

storage space are available.

Turing, who has been called the "father of computer science,"

also described the "Turing machine"—a theoretical machine

with an infinitely long tape and a read/write head that moves

along the tape, changing the values along the way. Clearly,

such a machine could never be built, but the model could

simulate the computation of algorithms that can be

performed on modern computers

## 7.

Shannon went on to found the field of information theorywith his 1948 paper on "A Mathematical Theory of

Communication." In it, he applied probability theory to the

problem of how to best encode the information a sender

wants to transmit. This work is one of the theoretical

foundations for many areas of study, including data

compression and cryptography.

During the 1940s, with the onset of electronic digital

equipment, the phrase computing machines gradually gave

away to just computers, referring to machines that performed

the types of calculations done by human clerks in earlier

years.

Over time, as it became clear that computers could be used

for more than just mathematical calculations, the field of

computer science broadened to study computation in

general and branched into many subfields, such as artificial

intelligence. Computer science began to be established as a

distinct academic discipline in the 1960s, with the creation of

the first computer science departments and degree

programs.[4]

## 8.

In 1975 Bill Gates cofounded Micro-Soft, later known asMicrosoft Corporation, with former classmate Paul Allen.

Landing lucrative deals developing the operating systems for

the computers of that time, and employing aggressive

marketing practices, Microsoft became the largest software

company in the world. Currently, its premiere product, the

Windows operating system, dominates the market by several

orders of magnitude.

One year after Gates founded Microsoft, another young man,

Steve Jobs founded Apple Computer Co. with Steve Wozniak.

From 1976 onward, Apple led the personal computer market

with its Apple I, II, and III lines of desktop computers, until

IBM (International Business Machines Corporation) released

its IBM-PC in 1980. The rivalry between Apple and Microsoft

has continued well into the twenty-first century, with Apple

possessing a relatively small portion of the computer market.

With computers getting smaller and more powerful, they

have become indispensable to modern life, and some are

even used in decision-making capacities