It's the 1970s. At work, we rely on typewriters. If we need to copy a document, we likely use a mimeograph or carbon paper. Few have heard of microcomputers, but two young computer enthusiasts, Bill Gates and Paul Allen, see that personal computing is a path to the future.

In 1975, Gates and Allen form a partnership called Microsoft. Like most start-ups, Microsoft begins small, but has a huge vision--a computer on every desktop and in every home. During the next years, Microsoft begins to change the ways we work.

Microsoft works on the first version of a new operating system. Interface Manager is the code name and is considered as the final name, but Windows prevails because it best describes the boxes or computing "windows" that are fundamental to the new system. Windows is announced in 1983, but it takes a while to develop. Skeptics call it "vaporware."

On November 20, 1985, two years after the initial announcement, Microsoft ships Windows 1.0. Now, rather than typing MS-DOS commands, you just move a mouse to point and click your way through screens, or "windows." Bill Gates says, "It is unique software designed for the serious PC user."

There are drop-down menus, scroll bars, icons, and dialog boxes that make programs easier to learn and use. You're able to switch among several programs without having to quit and restart each one. Windows 1.0 ships with several programs, including MS-DOS file management, Paint, Windows Writer, Notepad, Calculator, and a calendar, card file, and clock to help you manage day-to-day activities. There's even a game--Reversi.

Geek trivia: Remember floppy disks and kilobytes? Windows 1.0 requires a minimum of 256 kilobytes (KB), two double-sided floppy disk drives, and a graphics adapter card. A hard disk and 512 KB memory is recommended for running multiple programs or when using DOS 3.0 or higher.

On December 9, 1987 Microsoft releases Windows 2.0 with desktop icons and expanded memory. With improved graphics support, you can now overlap windows, control the screen layout, and use keyboard shortcuts to speed up your work. Some software developers write their first Windows-based programs for this release.

Windows 2.0 is designed for the Intel 286 processor. When the Intel 386 processor is released, Windows/386 soon follows to take advantage of its extended memory capabilities. Subsequent Windows releases continue to improve the speed, reliability, and usability of the PC.

In 1988, Microsoft becomes the world's largest PC software company based on sales. Computers are starting to become a part of daily life for some office workers.

Geek trivia: Control Panel makes its first appearance in Windows 2.0.

On May 22, 1990, Microsoft announces Windows 3.0, followed shortly by Windows 3.1 in 1992. Taken together, they sell 10 million copies in their first two years, making this the most widely used Windows operating system yet. The scale of this success causes Microsoft to revise earlier plans. Virtual Memory improves visual graphics. In 1990 Windows starts to look like the versions to come.

Windows now has significantly better performance, advanced graphics with 16 colors, and improved icons. A new wave of 386 PCs helps drive the popularity of Windows 3.0. With full support for the Intel 386 processor, programs run noticeably faster. Program Manager, File Manager, and Print Manager arrive in Windows 3.0.

Windows software is installed with floppy discs bought in large boxes with heavy instruction manuals.

The popularity of Windows 3.0 grows with the release of a new Windows software development kit (SDK), which helps software developers focus more on writing programs and less on writing device drivers.

Windows is increasingly used at work and home and now includes games like Solitaire, Hearts, and Minesweeper. An advertisement: "Now you can use the incredible power of Windows 3.0 to goof off."

Windows for Workgroups 3.11 adds peer-to-peer workgroup and domain networking support and, for the first time, PCs become an integral part of the emerging client/server computing evolution.

On August 24, 1995, Microsoft releases Windows 95, selling a record-setting 7 million copies in the first five weeks. It's the most publicized launch Microsoft has ever taken on. Television commercials feature the Rolling Stones singing "Start Me Up" over images of the new Start button. The press release simply begins: "It's here."

This is the era of fax/modems, email, the new online world, and dazzling multimedia games and educational software. Windows 95 has built-in Internet support, dial-up networking, and new Plug and Play capabilities that make it easy to install hardware and software. The 32-bit operating system also offers enhanced multimedia capabilities, more powerful features for mobile computing, and integrated networking.

At the time of the Windows 95 release, the previous Windows and MS-DOS operating systems are running on about 80 percent of the world's PCs. Windows 95 is the upgrade to these operating systems. To run Windows 95, you need a PC with a 386DX or higher processor (486 recommended) and at least 4 MB of RAM (8 MB of RAM recommended). Upgrade versions are available for both floppy disk and CD-ROM formats. It's available in 12 languages.

Windows 95 features the first appearance of the Start menu, taskbar, and minimize, maximize, and close buttons on each window.

In the early 1990s, tech insiders are talking about the Internet--a network of networks that has the power to connect computers all over the world. In 1995, Bill Gates delivers a memo titled "The Internet Tidal Wave," and declares the Internet as "the most important development since the advent of the PC."

In the summer of 1995, the first version of Internet Explorer is released. The browser joins those already vying for space on the World Wide Web.

Geek trivia: In 1996, Microsoft releases Flight Simulator for Windows 95--the first time in its 14-year history that it's available for Windows.

Released on June 25, 1998, Windows 98 is the first version of Windows designed specifically for consumers. PCs are common at work and home, and Internet cafes where you can get online are popping up. Windows 98 is described as an operating system that "Works Better, Plays Better."

With Windows 98, you can find information more easily on your PC as well as the Internet. Other improvements include the ability to open and close programs more quickly, and support for reading DVD discs and universal serial bus (USB) devices. Another first appearance is the Quick Launch bar, which lets you run programs without having to browse the Start menu or look for them on the desktop.

Geek trivia: Windows 98 is the last version based on MS-DOS.

Designed for home computer use, Windows Me offers numerous music, video, and home networking enhancements and reliability improvements compared to previous versions.

First appearances: System Restore, a feature that can roll back your PC software configuration to a date or time before a problem occurred. Movie Maker provides users with the tools to digitally edit, save, and share home videos. And with Microsoft Windows Media Player 7 technologies, you can find, organize, and play digital media.

Geek trivia: Technically speaking, Windows Me was the last Microsoft operating system to be based on the Windows 95 code base. Microsoft announced that all future operating system products would be based on the Windows NT and Windows 2000 kernel.

More than just the upgrade to Windows NT Workstation 4.0, Windows 2000 Professional is designed to replace Windows 95, Windows 98, and Windows NT Workstation 4.0 on all business desktops and laptops. Built on top of the proven Windows NT Workstation 4.0 code base, Windows 2000 adds major improvements in reliability, ease of use, Internet compatibility, and support for mobile computing.

Among other improvements, Windows 2000 Professional simplifies hardware installation by adding support for a wide variety of new Plug and Play hardware, including advanced networking and wireless products, USB devices, IEEE 1394 devices, and infrared devices.

Geek trivia: The nightly stress test performed on Windows 2000 during development is the equivalent of three months of run time on up to 1,500 computers.

On October 25, 2001, Windows XP is released with a redesigned look and feel that's centered on usability and a unified Help and Support services center. It's available in 25 languages. From the mid-1970s until the release of Windows XP, about 1 billion PCs have been shipped worldwide.

For Microsoft, Windows XP will become one of its best-selling products in the coming years. It's both fast and stable. Navigating the Start menu, taskbar, and Control Panel are more intuitive. Awareness of computer viruses and hackers increases, but fears are to a certain extent calmed by the online delivery of security updates. Consumers begin to understand warnings about suspicious attachments and viruses. There's more emphasis on Help and Support.

Windows XP Home Edition offers a clean, simplified visual design that makes frequently used features more accessible. Designed for home use, Windows XP offers such enhancements as the Network Setup Wizard, Windows Media Player, Windows Movie Maker, and enhanced digital photo capabilities.

Windows XP Professional brings the solid foundation of Windows 2000 to the PC desktop, enhancing reliability, security, and performance. With a fresh visual design, Windows XP Professional includes features for business and advanced home computing, including remote desktop support, an encrypting file system, and system restore and advanced networking features. Key enhancements for mobile users include wireless 802.1x networking support, Windows Messenger, and Remote Assistance.

Windows Vista is released in 2006 with the strongest security system yet. User Account Control helps prevent potentially harmful software from making changes to your computer. In Windows Vista Ultimate, BitLocker Drive Encryption provides better data protection for your computer, as laptop sales and security needs increase. Windows Vista also features enhancements to Windows Media Player as more and more people come to see their PCs as central locations for digital media. Here you can watch television, view and send photographs, and edit videos.

Design plays a big role in Windows Vista, and features such as the taskbar and the borders around windows get a brand new look. Search gets new emphasis and helps people find files on their PCs faster. Windows Vista introduces new editions that each have a different mix of features. It's available in 35 languages. The redesigned Start button makes its first appearance in Windows Vista.

Geek trivia: More than 1.5 million devices are compatible with Windows Vista at launch.

Windows 7 is released for the wireless world of the late 2000s. Laptops are outselling desktops, and it's become common to connect to public wireless hotspots in coffee shops and private networks in the home.

Windows 7 includes new ways to work with windows--like Snap, Peek, and Shake--that improves functionality and makes the interface more fun to use. It also marks the debut of Windows Touch, which lets touchscreen users browse the web, flip through photos, and open files and folders.

Geek trivia: Windows 7 is evaluated by 8 million beta testers worldwide before it's released.

Windows 8 is a reimagined operating system, from the chipset to the user experience, and introduces a totally new interface that works smoothly for both touch and mouse and keyboard. It functions as both a tablet for entertainment and a full-featured PC for getting things done. Windows 8 also includes enhancements of the familiar Windows desktop, with a new taskbar and streamlined file management.

Windows 8 features a Start screen with tiles that connect to people, files, apps, and websites. Apps are front and center, with access to a new place to get apps--the Windows Store--built right in to the Start screen.

Along with Windows 8, Microsoft also launches Windows RT, which runs on some tablets and PCs. Windows RT is designed for sleek devices and long battery life, and exclusively runs apps from the Windows Store. It also comes with a built-in version of Office that's optimized for touchscreens.

Geek trivia: Power users notices that Windows 8 makes the detection and correction of file system errors both more transparent and less intrusive.

Windows 8.1 advances the Windows 8 vision of providing a powerful collection of apps and cloud connectivity on great devices; it's everything people loved about Windows 8, plus some enhancements.

Windows 8.1 combines Microsoft's vision of innovation with customer feedback on Windows 8 to provide many improvements and new features: more Start screen personalization options that sync across all devices, the option to boot directly to the desktop, Bing Smart Search so you can find what you're looking for across the PC or the web, a Start button to navigate between the desktop and Start Screen, and more flexible options for viewing multiple applications at once on one or all screens. There are also several new built-in apps such as Bing Food & Drink, Bing Health & Fitness, and great utility apps like Reading List, Calculator, and Alarms. Many of the great apps shipped in Windows 8 are back and even better, making your experience more enjoyable right from the start.

In addition to these user experience changes, Windows 8.1 includes new and improved features like Workplace Join and Work Folders that enable Windows devices to connect more easily to corporate resources.

Geek trivia: Power users with multi-monitors can now have up to four apps from the Windows Store per screen appear on each monitor connected to the PC.