A personal computer is a general-purpose computer whose size, capabilities and original sale price make it useful for individuals, and is intended to be operated directly by an end-user with no intervening computer operator. This contrasts with the batch processing or time-sharing models that allowed larger, more expensive minicomputer and mainframe systems to be used by many people, usually at the same time. A related term is "PC" that was initially an acronym for "personal computer", but later became used primarily to refer to the ubiquitous Wintel platform.

Software applications for most personal computers include, but are not limited to, word processing, spreadsheets, databases, web browsers and e-mail clients, digital media playback, games and myriad personal productivity and special-purpose software applications. Modern personal computers often have connections to the Internet, allowing access to the World Wide Web and a wide range of other resources. Personal computers may be connected to a local area network (LAN), either by a cable or a wireless connection. A personal computer may be a desktop computer or a laptop, netbook, tablet or a handheld PC.

Early computer owners usually had to write their own programs to do anything useful with the machines, which even did not include an operating system. The very earliest microcomputers, equipped with a front panel, required hand-loading of a bootstrap program to load programs from external storage (paper tape, cassettes, or eventually diskettes). Before very long, automatic booting from permanent read-only memory became universal. Today's users have access to a wide range of commercial software, freeware and free and open-source software, which are provided in ready-to-run or ready-to-compile form. Software for personal computers, such as applications and video games, are typically developed and distributed independently from the hardware or OS manufacturers, whereas software for many mobile phones and other portable systems is approved and distributed through a centralized online store.[1][2]

Since the early 1990s, Microsoft operating systems and Intel hardware have dominated much of the personal computer market, first with MS-DOS and then with Windows. Popular alternatives to Microsoft's Windows operating systems include Apple's OS X and free open-source Unix-like operating systems such as Linux and BSD. AMD provides the major alternative to Intel's processors.

The Programma 101 was the first commercial "desktop personal computer", produced by the Italian company Olivetti and invented by the Italian engineer Pier Giorgio Perotto, inventor of the magnetic card system. The project started in 1962. It was launched at the 1964 New York World's Fair, and volume production began in 1965, the computer retailing for $3,200.[3][unreliable source?]

NASA bought at least ten Programma 101s and used them for the calculations for the 1969 Apollo 11 Moon landing. Then ABC used the Programma 101 to predict the presidential election of 1969, and the U.S. military used the machine to plan their operations in the Vietnam War. The Programma 101 was also used in schools, hospitals, government offices. This marked the beginning of the era of the personal computer.

In 1968, Hewlett-Packard was ordered to pay about $900,000 in royalties to Olivetti after their Hewlett-Packard 9100A was ruled to have copied some of the solutions adopted in the Programma 101, including the magnetic card, the architecture and other similar components.[3]

The Soviet MIR series of computers was developed from 1965 to 1969 in a group headed by Victor Glushkov. It was designed as a relatively small-scale computer for use in engineering and scientific applications and contained a hardware implementation of a high-level programming language. Another innovative feature for that time was the user interface combining a keyboard with a monitor and light pen for correcting texts and drawing on screen.[4]

In what was later to be called the Mother of All Demos, SRI researcher Douglas Engelbart in 1968 gave a preview of what would become the staples of daily working life in the 21st century: e-mail, hypertext, word processing, video conferencing and the mouse. The demonstration required technical support staff and a mainframe time-sharing computer that were far too costly for individual business use at the time.

By the early 1970s, people in academic or research institutions had the opportunity for single-person use of a computer system in interactive mode for extended durations, although these systems would still have been too expensive to be owned by a single person.

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