Before 1984, personal computers generally were powered by drab command-line operating systems that displayed characters in a single font. The introduction of the Apple Macintosh and its Mac OS operating system in 1984 changed everything, making the graphical user interface or "GUI"- in this case, the use of a mouse to navigate a virtual desktop - commercially successful. While Apple did not invent the GUI (that honor is generally credited to Xerox), Mac OS was revolutionary and introduced consumers to concepts such as the use of a mouse as a pointing device and onscreen rendering of multiple fonts. Virtually every consumer operating system in use still follows this fundamental structure.

2001 was an enormously important year for Apple, and the release of the iPod is the top reason why. The iPod was not the first hard disk-based MP3 player, but it was the first to gain major commercial success. Likely due to its simple interface and attractive design, it gained major traction and, along with iTunes, helped changed the perception of music being packaged in a digital medium. The iPod revitalized Apple as a company and was the catalyst that has enabled all of their subsequent innovations.

The Apple II computer was one of the first highly successful personal computers. The platform remained a mainstay in personal computing well into the 1990s, particularly in American schools. Its color graphics and floppy disk capability (along with a relatively affordable price for the time, starting at $1298) helped establish Apple as a computer company and a force of innovation. Moreover, the VisiCalc program for the Apple II was the first spreadsheet program for personal computers, a major event in the world of business computing.

While they are hard to segregate from the iPod, iTunes and the iTunes Store (which now sells music, videos, apps, and, thanks to the iPad, books) were perhaps even more revolutionary than the device itself. With the iTunes Store, Apple coaxed record labels (and later, movie and television studios) into the digital age. It is now the top music vendor in America, serving up over 10 billion song downloads in just its first seven years. The iTunes application enabled that success, popularized the database approach to media management, and introduced many PC users to Apple software.

The iPod was the device that made Apple a serious player in the tech industry again; the iPhone is the device that pushed Apple (and its stock price) into the stratosphere. The iPhone is the best-selling smartphone on the market (with over 40 million sold) and was introduced in 2007 with an innovative, multitouch interface and feature-set that competitors have rarely matched. The genius of the iPhone is in the simplicity of its touch interface and its adaptability; with the right software or "app" (the term it helped popularize), it can serve nearly any function the hardware is capable of.

Simply put, the iMac saved Apple. Following founder Steve Jobs' return to the company in 1997 and a cash infusion from rival Microsoft, Apple refocused and delivered a simplified computer reminiscent of the original Macintosh. The iMac set a trend in its abandonment of a floppy disk drive and was the first major product designed by resident wizard Jonathan Ive (who also designed the iPod and iPhone). Most importantly, it helped restore Apple to profitability and gave the company a new lease on life.

Apple's LaserWriter printer was the first printer to ship with Adobe's PostScript interpreter technology, which allowed printing of multiple fonts and graphics in complex layouts on a single page. The LaserWriter redefined what was possible in desktop printing and - despite its retail price of $6,995 - is credited with sparking the desktop publishing revolution, which began in full swing with the release of Aldus' Pagemaker for the Macintosh in late 1985.

The PowerBook set a standard in laptop design that all competitors eventually followed. It was the first laptop to feature a keyboard positioned away from the user to allow for a palm rest and trackball, just like all standard laptops today. The PowerBook 500, released in 1995, was the first laptop to feature a trackpad, which is also universal now. The first PowerBook was a hit, capturing 40 percent of the market, and the line remained vital for Apple until the release of the MacBook in 2006.

The most recent major revision of Mac OS, OS X enabled Apple to mount a serious, ongoing challenge to Microsoft's dominant Windows operating system. While OS X's overall market share still hovers in the mid-high single digits, it has made major inroads in the home and laptop computer markets and is the second most-used operating system in the world by a significant margin. There have been six major upgrades to OS X each time enhancing the user experience without requiring a major overhaul. Its fifth and most significant, 2007's Leopard, enabled Intel CPU and 64 bit support, allowing Apple to utilize the best processors available.

Apple has long tried to limit the use of its software to its own hardware, and the company applied this same concept to retail marketing with the opening of its first Apple Store in 2001 in Virginia. These stores, which sell both Apple wares and compatible third-party products, strengthened Apple's brand, gave it increased control over product rollouts, and offered a local tech support services for its products. There are now 287 (and counting) Apple Stores across the globe, and competitor Microsoft responded by opening its own, similar stores in 2009.

The Apple Newton platform was ultimately a financial bust, but was revolutionary in that it was among the first personal digital assistants - or PDAs - to hit the market. In fact, the term PDA was coined by then-Apple CEO John Sculley during Newton's development. Newton, and the MessagePad devices it ran on, relied primarily on handwriting recognition, much like PDAs later made by Palm and other competitors. Apple's platform and hardware helped paved the way for stylus-based PDAs as well as the Blackberrys and iPhones that have replaced them.

Apple's iLife software suite has been a significant weapon in the company's campaign against the dominant Windows platform. The suite, which includes photo (iPhoto), video (iMovie, iDVD), web (iWeb), and music (GarageBand) editing programs is now included with new Mac computers and allows Apple to argue that their computers - which are generally sold at premium price points - offer comparable value to their Windows counterparts and are superior for non-business functions.

The iPad - the non-3G version of which is being released this Saturday - is Apple's second foray into the realm of tablet computing, following its unsuccessful Newton platform. Time will tell if the iPad will be another hit for the company or the first big miss for a major new product since the iPhone's release. The iPad is effectively a jumbo iPhone/iPod Touch and takes aim at eReaders and netbooks, offering greater functionality than the former and a smaller form-factor (and lots more glitz) than the latter. Whatever its long-term prognosis, we're betting that it's going to be a scarce item to find on shelves for the foreseeable future.