In the 20 years since Linux 1.0 first appeared, the open source operating system has become one of the major winners in the enterprise data center, alongside Microsoft Windows. Linux also has a presence on the public Internet and in public cloud services.
1. "LINUX", is a directoryname on FUNET - Linux Torvalds wanted to name his kernel "Freax". Well the name is a combination of words "freak" and "free", and then the final X to represent its similarity with the Unix operating system. When the initial code was uploaded to an FTP server, the server administrator didn't like the name Freax, and he suggested the name Linux and gave a directory on the ftp server. The directory on the ftp server was called "linux".
2. Linux is only the kernel - Linux is not an OS, but it is the kernel, GNU Linux is the OS and it comes in several hundred flavours.
3. Microsoft Contributes to Linux Kernel Development - Yes the company whose main philosophy rests on proprietary software development, also contributes to Linux. It even went ahead of Canonical once, in the number of lines of code contributed to kernel. But, do not think that Microsoft is contributing to kernel development for improving the kernel. Its for better support of Hyper-V hypervisor on Linux.