Although Microsoft's original Windows upgrade offer has largely ended, it is still possible to upgrade to 10 for free by various means. Users of assistive technologies such as text-to-speech, for example, are entitled to a free upgrade to Windows 10. Many methods of upgrading to 10 for free will expire by December 31, 2017, meaning that as time passes, 10 is likely to become more expensive.
Unlike .zip files, which Windows 10 is able to open without external software, Windows 10 requires an application like 7zip to open .rar files. The operating system itself does not provide the user with any options for opening .rar archive files.
There are various applications built in to Windows that will tell you what graphics card you are using. The most straightforward is dxdiag, which can usually be opened simply by typing "dxdiag" into the Start Menu and pressing Enter. The first page that dxdiag displays will tell you information like your processor and memory. Click "Display 1" (or similar) at the top to view your graphics card or cards.
Most installations of Win10 are 64-bit. If your computer is 64-bit, it likely came with a 64-bit version of Windows 7 or 8.1, which will upgrade to the 64-bit version of 10. An installation of 10 without a separate "Program Files (x86)" folder is almost always 32-bit.
As of this writing, though Win10 comes with Windows Media Player, it is not reliable for playing DVDs natively. To best play DVDs, use a third-party application, like VLC Media Player.
While running Win10, type "about" in the Start Menu and select "About this PC". Under "Edition", you will see what version of Windows 10 (Pro, Enterprise, ...) you are running.
As with most previous versions of Windows, Win10 cannot read ext4 partitions, used by Linux and other operating systems, by default. Certain advanced software can allow Windows to read or even write from ext4 partitions.
In an early conference, Microsoft claimed that 10 will be the last major release of Windows, and operating system changes will all occur to 10. As of this writing, that claim is still true.
You can press the Windows and PrntScrn (or PrtSc, ...) keys together, which will save a screenshot under the Screenshots folder in the Pictures library. Otherwise, you may use the built-in Snipping Tool to create screenshots using the mouse.
To change your Cortana settings, type "Cortana" in the Start Menu and then launch Cortana. You may turn her off or on in Settings by clicking on the gear icon on the left-hand side.