Computer

A computer is a machine that can be programmed to do tasks on its own. It follows steps to do arithmetic or logical operations. Modern digital electronic computers run many tasks using sets of rules called programs.

Computers are in many things we use every day, like microwave ovens, personal computers, and smartphones. They help run the Internet, linking people and devices all over the world.

Early computers were made just for simple calculations. Now, they are faster, stronger, and can do more things than before, changing how we live, work, and have fun.

Etymology

The word "computer" used to mean a person who did calculations. In 1613, a book used the word to describe someone who solved math problems. In the 1640s, it still meant a person who worked with numbers. Women often had these jobs because they could be paid less.

By 1897, the word began to mean a machine that calculates. Today, "computer" means the digital electronic machines we use, a meaning that started in 1945. These machines can do much more than just calculations now.

Main article: Turing machine

History

Main articles: History of computing and History of computing hardware

For a chronological guide, see Timeline of computing.

Devices have been used for counting and calculations for thousands of years, often with fingers. Early tools like tally sticks and counting rods were common. The abacus, used for arithmetic, dates back to ancient times, with the Roman abacus developed from Babylonian devices around 2400 BCE.

The Antikythera mechanism, found in 1901, is thought to be the earliest known mechanical device for calculating astronomical positions, dating to around 100 BCE. Many mechanical tools were made for astronomy and navigation, like the astrolabe, invented in the Hellenistic world. In the 1770s, a Swiss watchmaker made a mechanical doll that could write messages by changing its internal wheels.

Charles Babbage, an English engineer, created the idea of a programmable computer in the early 19th century. He designed the first mechanical computer but could not finish it due to money problems. Later, electromechanical machines let users input problems through keyboards and get results.

During the first half of the 20th century, many scientific needs were met by analog computers, which used physical models for calculations. These were not as versatile as modern digital computers. The first modern analog computer was a tide-predicting machine from 1872.

Digital computers began with electromechanical devices, where electric switches controlled mechanical parts. Konrad Zuse built one of the earliest examples in 1939. Later, purely electronic computers using vacuum tubes became common. The ENIAC, built in the U.S., was one of the first electronic programmable computers.

The principle of the modern computer was proposed by Alan Turing in 1936. He described a machine that could run different programs stored in memory. This idea led to the stored-program computer, where instructions are kept in memory.

Transistors replaced vacuum tubes in the 1950s, making computers smaller, faster, and more reliable. Integrated circuits, which put many transistors on a single chip, were invented in the late 1950s. These allowed for the microprocessors that power today's computers.

The first mobile computers were large and needed power from outlets. Later, portable computers and laptops became smaller and could run on batteries. Today, smartphones and tablets are the most common computers, using tiny chips to perform complex tasks.

Types

See also: Classes of computers

Computers can be grouped in many ways. One way is by their design. There are analog computers, digital computers, and hybrid computers. Another way is by their size and what they are used for. This includes very large supercomputers, smaller mainframe computers, and personal computers like laptops and desktops. There are also tiny computers like smartwatches and smartphones.

Some computers are not electronic. For example, a person who does math by hand can be called a computer. Any device that can process information can be considered a computer.

Hardware

Hardware includes all the parts you can touch on a computer. These parts include chips, graphic cards, sound cards, memory, motherboards, screens, power supplies, cables, keyboards, printers, and computer mice. These pieces work together to help the computer do its job.

A computer has four main parts: the arithmetic logic unit (ALU), the control unit, memory, and input and output devices (I/O). These parts are connected by wires and work together using tiny electrical circuits. These circuits help the computer process data and run programs.

Software

Main article: Software

Software is the set of instructions that tells a computer what to do. Unlike the physical parts of a computer, called hardware, software cannot be touched. It includes programs, libraries, and data like online help or digital media. Software is usually divided into two types: system software, which helps the computer work, and application software, which does specific jobs for users.

One important feature of modern computers is that they can be programmed. This means they can follow sets of instructions, called programs, to do many different tasks. These programs can be small or large, and they help computers do things like writing words or looking at websites. Even though computers can follow billions of instructions each second, sometimes mistakes, called bugs, can happen. These bugs are usually because of errors made by the people who write the programs, not the computer itself.

Networking and the Internet

Computers help us share information from one place to another. This started in the 1950s. One early system was used by the U.S. military and was called SAGE.

In the 1970s, researchers in the United States connected their computers using a network called the ARPANET. This showed how computers could work together over long distances.

Today, artificial intelligence depends on code written by people. With better hardware like graphics processing units (GPUs), machine learning has become stronger. Some advanced models can help control computers or robots.

Professions and organizations

As computers became more common, many new jobs appeared. These jobs include programming, designing computer parts, and managing computer networks.

Because computers need to work together, many groups formed. These groups help create rules and support computer users. They can be official bodies or informal clubs, all working to help computers communicate and work well.