A kernel that many operating systems called "linux distros" are based off of. Linux is known mainly for being open source, and in most cases, also free to use. Many linux distros are do-it-yourself operating systems, and some come with a full GUI, and many automatic features, which makes it easier for normal people to use. These easy-to-use linux distros are commonly used as a price-effective and useful platform for public and private access to computers, and on servers. Many people criticize this operating system for not being able to run most applications, specifically games. Linux is somewhat limited to which applications it can run, but many people have made alternatives to those applications, and even ways to run those applications inside linux. In fact, many popular games can run on linux, contrary to the packaging of the game. Overall, linux is a great kernel that formed many popular and useful operating systems, which are in use by millions of people today. Linux is also available in a liveCD format, which lets users try linux before they fully install it.
"Hey, can you help me with my computer, windows crashed on me again."
"Oh, I'm sorry, I use linux, and I'm not too fond of microsoft products."
"Dude, linux sucks! It can't even run games!"
"Actually, unless you're planning to install every game on the market that was ever made, linux is actually a pretty good gaming platform. The only advice I can give you is to use linux. Here's a LiveCD"
"Okay, I guess I could try it."
2 days later.....
"What the hell man, when I tried to instal your stupid linux, it erased my windows!"
"Did you read the back of the CD? It clearly says that by default it'll erase all existing software, unless you partition your drive or install it inside windows. See, it says it right here on the CD."
"Well, it should've warned me!"
"Dude, maybe you should've just RTFM