Hello @suos.
Well, Linux is an operative system, just like Windows. With Linux you can do a lot of things: surf the web, edit documents, preview images, edit images, and of course, you can program with Linux. I prefer Linux over Windows because it has several tools installed per default that are useful for a programmer. Also, I find that doing some programming things in Linux are easier than doing them in Windows, it's lighter and it's more secure too. In this guide, everything that I do with Linux, can be exactly done with Windows as well, there are no differences, but it's not always like that.
Github is a web service that allows you to store and organize your code and keep track of all the changes that you made to your files. It's useful for medium-big projects and for sharing your code with a coworker or a partner who is using the same code that you are using. You can find more information in my previous post here.
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