Why Linux is best for server?

Linux is without doubt the most secure kernel out there, making Linux based operating systems secure and suitable for servers. To be useful, a server needs to be able to accept requests for services from remote clients, and a server is always vulnerable by permitting some access to its ports.

What OS do most servers run?

About 70% of servers are running Linux. Commonly-used distributions by Linux hosts include Ubuntu, CentOS, and Red Hat Linux. Though there are exceptions, applications available for one Linux distribution can be run using other distributions.