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Next month marks the 28th anniversary of Windows, Microsoft's iconic operating system and the backbone of what turned it into one of the most powerful companies in tech.

But before that, comes the next iteration of that software -- Windows 8.1. It goes out as a free update to existing Windows 8 users on Thursday, and puts Microsoft in a new direction of offering smaller updates more frequently, something that's now expected by consumers who are used to major releases once a year (or more) on smartphones and tablets made by rivals.

You can read more about what's new and different in Windows 8.1 here, as well as CNET's review of the software. In the meantime, let's take a quick look at what came before it.

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Windows 1

Released November 20, 1985

The first version of Microsoft's Windows brought a graphical user interface and multitasking to desktop computing. Gone were command prompts in place of -- you guessed it -- windows that could be organized and moved around the screen on a virtual desktop.

Microsoft was not the first company to do this, nor was it the most successful with Windows 1.0, but it paved the way for future iterations that brought the company massive success.

Included in this first version, which cost $99 (about $216 adjusted for inflation) were some basic utilities like a clock and calculator. Microsoft also bundled in Windows Write and Paint.

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Windows 2

Released December 9, 1987

Two years after the initial version of Windows, came Windows 2.0. Its big, new trick was allowing application windows to appear on top of one another, creating a sense of depth. The software also let users place shortcuts to applications right on the desktop, and included new keyboard shortcuts.

Microsoft followed it up with two additional variations of the software to run on two different Intel processors, and handle multiple DOS applications at the same time -- a feature that was baked into later versions of Windows.

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Windows 3

Released May 22, 1990

Microsoft's third version of Windows brought a new look and feel with a touch of 3D, and included the popular Solitaire game. Behind the scenes, Microsoft changed the architecture of the software to address more memory and run on different types of processors.

Microsoft followed up with Windows 3.1, which added things like colorful screensavers and support for TrueType fonts. Microsoft also made the release faster and more stable, followed up by a version that added networking features.

Windows NT

Released July 27, 1993

Windows NT made its mark for being the first 32-bit version of Windows. The operating system could run on several types of Intel processors, and run multiple programs simultaneously, with up to 2GB of virtual memory apiece. Microsoft also promised better stability, keeping individually crashing software from bringing the entire system down.

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Windows 95

Released August 24, 1995

Windows 95 brought with it the advent of the Start button and taskbar, which became an iconic feature of Windows. Moreover, Windows 95 brought with it The Microsoft Network, the company's early foray into connected online services.

Buyers lined up for hours to get a copy of Windows 95 on launch day, and Microsoft pushed it out with a huge, $300 million ad campaign that featured The Rolling Stones hit "Start Me Up."

Tailing Windows 95 was Internet Explorer, which was released a month later as a paid side product within the "Internet Jumpstart Kit." It wasn't until IE 3.0 a year later that Microsoft began including it with Windows, something that became the jumping-off point for a major antitrust investigation against the company.

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Windows 98

Released June 25, 1998

Windows 98 brought with it an integrated version of Internet Explorer, marking the beginnings of the Internet-ready OS. Microsoft also reworked its file explorer to take cues from IE's user interface, added a fast shutdown option, and took steps toward making it simpler to update drivers and download system patches. There was even the addition of support for TV tuners, letting users watch TV on their computers if they had TV tuner circuit boards -- all part of an effort to bolster Microsoft's WebTV service.

Microsoft followed it up with "Windows 98 Second Edition" a year later, which included a newer version of IE and added polish to various built-in software and tools.

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Windows 2000/Windows ME

Released February 17, 2000 and September 14, 2000

Originally named "NT 5.0" Microsoft's Windows 2000 promised a speed boost compared with earlier versions of Windows, and was aimed at large organizations and corporations.

Months later, Microsoft followed up with Windows Millennium Edition (ME), what was then seen as an in-between version of the OS that added home-networking features, along with new software for digital music and video editing. It also promised faster boot times, and simpler tech support options, but ran applications slower than Windows 98.

The software was quickly replaced with Windows XP just a year later.

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Windows XP

Released October 25, 2001

Windows XP was a drastic overhaul to the look and feel of previous iterations of Windows, while retaining many of its core features and functionality. Moreover, it was a big move by Microsoft to connect parts of its various online services to the OS.

XP got off to a slow start, due in no small part to stiff hardware requirements, but eventually gained popularity and ended up holding onto its top spot among operating systems thanks to a tepid response to Windows Vista, which arrived in 2007. Many consumers as well as businesses decided to hold off on that update until Windows 7 arrived two years later.

Windows Vista

Released January 30, 2007

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Windows Vista was largely an attempt to polish the highly successful Windows XP and rethink several core Windows features.

New features included a more modern user interface Microsoft dubbed "Aero," additional security measures, and better search. Microsoft also reworked some of its built-in productivity and entertainment software, like mail, calendar, DVD maker, and photo gallery.

Vista took longer than previous iterations to arrive. It also brought the ire of some users, who disliked the new software security features and more stringent hardware requirements. Many of the concerns centered around stability and compatibility with older software, as well as the cost of the update -- something Microsoft adjusted with a price cuta year after the software's release.

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Windows 7

Released October 22, 2009

Windows 7 brought a new, more polished look to its predecessor, and did away with many of the annoyances that made Vista a dud.

Visually, Microsoft revamped the Windows taskbar in 7 to let users "pin" programs, and quickly view previews of open software. It also added shortcuts for launching popular tasks within open applications with something called Jump lists, as well as a way to quickly organize open windows by "snapping" them to corners of the screen.

Other tweaks include some more advanced and systemwide touch-navigation features, and improvements to search, general system performance, and the built-in Media Player software.

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Windows 8

Released October 26, 2012

Windows 8's big trick was bringing Microsoft into the tablet era, with a more touch-friendly interface.

That change involved what Microsoft then called the "Metro" interface and a new series of touch-ready apps for photos, video, mail, and music. Microsoft also included a built-in store for users to find and download new software.

Microsoft didn't go all the way toward a touch-ready future, however. The company included a legacy "desktop" mode that could run traditional Windows apps with the usual look and feel similar to that of Windows 7.

Behind the scenes, Windows 8 also brought Windows into new territory, supporting chips made by ARM Holdings -- the low-power chips that helped fuel the rise and prevalence of smartphones and tablets. Despite that, most consumers, developers, and later hardware manufacturers opted to go with the version of Windows running on x86 processors, which was backwards compatible with older programs.

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Windows 8.1

Released October 17, 2013

Windows 8.1 represents a slight departure for Microsoft, with a smaller upgrade that comes free of charge to existing Windows 8 users.

The update is a collection of user interface tweaks, along with a handful of behind-the-scenes changes. Key among them is the option to boot straight to the desktop, as well as the return of the Start button to launch apps. On the back end, Microsoft's added deeper integration with its SkyDrive cloud service, along with Miracast for wireless streaming over Wi-Fi to other Miracast-enabled devices.

Other additions include an amped-up search tool that can dig through files stored locally as well as on SkyDrive, support for 3D printing, a new Xbox Music app, and better support for users with multi-monitor setups.

Windows 8.2/9?

The big question is what's coming down the pike next from Redmond. Will it be another bite-size update in faster succession like Windows 8.1, or another big jump the likes of Windows 7 or 8?

Per Mary Jo Foley of ZDNet, CNET's sister site, we're more likely to see the latter -- a big jump -- in early 2015, with another major release that could blend Microsoft's Windows OS for desktops with its Windows Phone OS.

Such a possibility could mean big changes in how Windows hardware is made, and what software developers need to do to create software. It could also drastically simplify and cohere what is currently a disparate Windows experience. The only thing that seems certain is that it won't be the last Windows.