what is linux?

     To kind of explain what Linux is is you have to explain what an operating system is.
And the thing about operating system is, you, I mean you are never ever supposed to see it.
Because nobody really uses an operating system, people use programs on their computer,and the only mission in life of an operating system is to help those programs run.
So an operating system never dose anything on it's own.
It's only waiting for the programs to ask for certain resources or ask for some files on the disks or ask for the programs to connect them to the outside world.And then the operating system comes, steps in and then tries to make it easy for people to write programs.

       要说清楚什么是Linux就一定要说清楚什么是操作系统。
要让你了解操作系统的麻烦是，你甚至不可能看到它。
因为没有人直接面对一个操作系统，人们面对的是他们的计算机上的某个程序。操作系统存在的唯一意义就是帮助这些程序运行。所以操作系统本身永远不主动地做任何事。
它只是在等待应用程序请求（计算机的）某些资源、或者请求（读取）硬盘上的某些文件、或者请求把它们连接到外面的世界，只有这样操作系统才开始动起来，它把这些请求完成，另外它还尽可能的让人们更容易的写出程序。