Computer

A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations. Modern digital electronic computers can run many different tasks because they follow sets of instructions called programs.

Computers are used in many everyday items, from simple devices like microwave ovens to powerful tools like personal computers and smartphones. They help run the Internet, connecting billions of people and devices around the world.

Early computers were built for basic calculations, but they have grown much more advanced over time. Today, computers are faster, more powerful, and more versatile than ever before, changing how we live, work, and play.

Etymology

The word "computer" originally meant a person who did calculations. In 1613, a book used the term to describe someone who figured out math problems. Later, in the 1640s, it still meant a person who calculated numbers. Women were often hired for this job because they could be paid less.

By 1897, the word started to mean a machine that calculates. Today, "computer" refers to the programmable digital electronic machines we use, a meaning that began 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 to help with counting and calculations for thousands of years, often using 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, discovered in 1901, is believed 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 created 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 funding issues. Later, electromechanical machines allowed users to 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 physical parts of a computer. These parts include circuits, chips, graphic cards, sound cards, memory, motherboards, displays, 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 that can be turned on or off. These circuits represent information as 1s and 0s, allowing the computer to 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 is not tangible. It includes programs, libraries, and data like online documentation or digital media. Software is usually divided into two types: system software, which helps the computer operate, and application software, which performs specific tasks for users.

One key feature of modern computers is that they can be programmed. This means they can follow sets of instructions, called programs, to perform many different jobs. These programs can be very small or very large, and they help computers do everything from writing words to browsing the web. Even though computers can execute billions of instructions each second, sometimes mistakes, called bugs, can occur. These bugs are usually due to errors made by the people who write the programs, not the computer itself.

Networking and the Internet

Computers have helped share information between different places since the 1950s. One early example was a system used by the U.S. military called SAGE. Later, 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.

During the 20th century, artificial intelligence mainly relied on code written by people. But now, with better hardware like graphics processing units (GPUs), machine learning has become more powerful. Some advanced models can even help control computers or robots.

Professions and organizations

As computers became more common in everyday life, many new jobs emerged that involve working with them. People now have careers such as programming, designing computer hardware, and managing computer networks.

Because computers need to work together and share information, many groups and organizations formed to create standards and support computer users. These groups can be official bodies or informal clubs, all focused on helping computers communicate and function properly.