From a strictly technology standpoint, except for Linux, both Microsoft Windows and Apple OS derive from the prototype UI used on the Xerox Alto PC at Xerox Palo Alto Research Center (PARC). Linux, as most of us know, is derived from Unix. Linus Torvalds took a good OS and made it better and much easier to use. You're totally right that without IBM and Microsoft, much of the technology used on computers would not exist. However, the PC, tablets, computer mice and most of the UI of both Apple OS and MS Windows would not have existed without Xerox PARC. So, yea, Apple didn't invent anything. They just took an existing product and built on it. So did Microsoft, which bought PC-DOS, changed the name to MS-DOS, and later put a desktop interface on top of it - creating MS Windows. The rest is mostly very good marketing and lots of good software programming. The fundamental Windows interface has not changed significantly since Windows 95, and MS-DOS still exists even in Windows 7. Windows 8, from what I've seen and read about it, is built on Windows 7 but has the Metro interface merged into it as well in an attempt to make it work on touchscreen tablets, laptops and desktop PC's. Sorry for being so long with this, but I mostly wanted to state why you're totally right and give everyone a little bit of history.
You want to thank any company for what we have in technology, thank Xerox. Thank the US Department of Defense's DARPA for the Internet. What we can thank Microsoft and Apple for is building on what Xerox started and making it affordable for the masses.
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