What is Linux?Linux is, in simplest terms, an operating system. It is the software on a computer that enables applications and the computer operator to access the devices on the computer to perform desired functions. As an open operating system, Linux is developed collaboratively, meaning no one company is solely responsible for its development or ongoing support. Companies participating in the Linux economy share research and development costs with their partners and competitors. This spreading of development burden amongst individuals and companies has resulted in a large and efficient ecosystem and unheralded software innovation.
What different distributions are available? 
Ubuntu is currently the most popular Linux distribution, and the world's most popular open-source OS. This is a good starting point for Linux beginners. The default Desktop Environment, Unity, is a bit slow, but many other DE's are available from the Ubuntu Software Center(sort of like an appstore for ubuntu). The community support is amazingly helpful. They have just about any problem you can think of already handled.
Debian is the most basic Linux distro you can ask for. Pretty much completely vanilla. Ubuntu and all of its variants stem from Debian. It comes with two DE's pre installed, GNOME and XFCE. You can always get a different one if you want.
Linux Mint is good for both experienced users and beginners. It has a wide variety of DE's to choose from as well.
Arch Linux is sort of like the final boss of Linux distros. It's probably the most difficult to use distro out there. New users should steer clear of this one. Also, you shouldn't ask their community for help. Apparently, they're just a bunch of starfishs.
Sound familiar?
Manjaro is a more user-friendly alternative to Arch. It is based on arch, but it is ready to use right out of the box. No partitioning, or lists of required packages, or bleeding-edge software. And since it's based on Arch, you can use the all-knowing amazingly helpful Arch Wiki. It's Arch made easy.
Elementary OS is a project that stems from Ubuntu. Like Ubuntu, Elementary has it's own special desktop environment called pantheon. If you like Mac OS x, then you will like this because the interface is pretty much the same. It's not as lightweight as other distros, but it looks amazing. If you prefer convenience and looks, but don't care for customization or lightweightness, this is what you are looking for.
And more!That's great, but what do I use it for?Linux is a very flexible platform. It works really well on lower-end computers. If you've got a laptop that is struggling to run Windows, then this is the OS for you. It is also extremely useful for networking. If you want a server computer, then this is something you should look out for.
How do I install it?On each website linked above, there is a download link somewhere for an iso. Burn that iso to a disc and then you have your install disk. After that just boot from it. It will tell you how to do the rest.
Where do I get news about Linux?Right here!
If you want support for a problem you are having, and the users here can't figure it out, then take a look at the Debian Wiki or post a topic on the distribution's forums. They'll figure it out for ya.
I know it's short for a megathread. I'll add more later.
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