The Macintosh 128K was released on January 24, 1984. It was the first commercially successful personal computer to feature a mouse and a graphical user interface (GUI) rather than a command line interface.

The Macintosh was introduced by the now famous US$1.5 million Ridley Scott television commercial, "1984". The commercial most notably aired during the third quarter of Super Bowl XVIII on 22 January 1984 and is now considered a "watershed event" and a "masterpiece."

1984 used an unnamed heroine to represent the coming of the Macintosh (indicated by her white tank top with a Picasso-style picture of Apple’s Macintosh computer on it) as a means of saving humanity from "conformity" (Big Brother). These images were an allusion to George Orwell's noted novel, Nineteen Eighty-Four, which described a dystopian future ruled by a televised "Big Brother."

The Macintosh project started in the late 1970s with Jef Raskin, an Apple employee, who envisioned an easy-to-use, low-cost computer for the average consumer. In September 1979, Raskin was authorised to start hiring for the project, and he began to look for an engineer who could put together a prototype.

Bill Atkinson, a member of Apple's Lisa team (which was developing a similar but higher-end computer), introduced him to Burrell Smith, a service technician who had been hired earlier that year. Over the years, Raskin assembled a large development team that designed and built the original Macintosh hardware and software; besides Raskin, Atkinson and Smith, the team included Chris Espinosa, Joanna Hoffman, George Crow, Jerry Manock, Susan Kare, Andy Hertzfeld, and Daniel Kottke.

Smith’s first Macintosh board was built to Raskin’s design specifications: it had 64 kilobytes (KB) of RAM, used the Motorola 6809E microprocessor, and was capable of supporting a 256×256 pixel black-and-white bitmap display. Bud Tribble, a Macintosh programmer, was interested in running the Lisa’s graphical programs on the Macintosh, and asked Smith whether he could incorporate the Lisa’s Motorola 68000 microprocessor into the Mac while still keeping the production cost down.

By December 1980, Smith had succeeded in designing a board that not only used the 68000, but bumped its speed from 5 to 8 megahertz (MHz); this board also had the capacity to support a 384×256 pixel display. Smith’s design used fewer RAM chips than the Lisa, which made production of the board significantly more cost-efficient.

The final Mac design was self-contained and had the complete QuickDraw picture language and interpreter in 64 Kb of ROM - far than most other computers; it had 128 KB of RAM, in the form of sixteen 64 kilobit (Kb) RAM chips soldered to the logicboard. Though there were no memory slots, its RAM was expandable to 512 KB by means of soldering sixteen chip sockets to accept 256 Kb RAM chips in place of the factory-installed chips. The final product's screen was a 9-inch, 512x342 pixel monochrome display, exceeding the prototypes.

The design caught the attention of Steve Jobs, co-founder of Apple. Realizing that the Macintosh was more marketable than the Lisa, he began to focus his attention on the project. Raskin finally left the Macintosh project in 1981 over a personality conflict with Jobs, and the final Macintosh design is said to be closer to Jobs’ ideas than Raskin’s.

After hearing of the pioneering GUI technology being developed at Xerox PARC, Jobs had negotiated a visit to see the Xerox Alto computer and Smalltalk development tools in exchange for Apple stock options. The Lisa and Macintosh user interfaces were partially influenced by technology seen at Xerox PARC and were combined with the Macintosh group's own ideas.

Jobs also commissioned industrial designer Hartmut Esslinger to work on the Macintosh line, resulting in the "Snow White" design language; although it came too late for the earliest Macs, it was implemented in most other mid- to late-1980s Apple computers. However, Jobs’ leadership at the Macintosh project was short-lived; after an internal power struggle with new CEO John Sculley, Jobs angrily resigned from Apple in 1985, went on to found NeXT, another computer company, and did not return until 1997.

Through the second half of the 1980s, the company established market share only to see it dissipate in the 1990s as the personal computer market shifted towards IBM PC Compatible machines running MS-DOS and Microsoft Windows.

Apple consolidated multiple consumer-level desktop models into the 1998 iMac all-in-one, which sold extremely well and saw the Macintosh brand revitalized. Current Mac systems are mainly targeted at the home, education, and creative professional markets. They are: the aforementioned (though upgraded) iMac and the entry-level Mac mini desktop models, the workstation-level Mac Pro tower, the MacBook, MacBook Air and MacBook Pro laptops, and the Xserve server.