What is Mir and why is it important?

I've heard a lot about Mir lately. It seems to be a big thing in the Ubuntu community.

What exactly is Mir and why is it so important? Will it affect me?

Mir

Mir is the next generation display server. A system-level component targeted as a replacement for the X window server system to unlock next-generation user experiences for devices ranging from Linux desktop to mobile devices powered by Ubuntu.

The purpose of Mir is to enable the development of the Next Generation Unity.

In the Linux world, the display server is the part of the software stack that handles graphics processing. In other words, it's the thing that draws pretty pictures on the screen. And for decades, there has been only one show in town when it came to display servers for virtually all open source operating systems: The X Window System, which was written in an era when the computing landscape was very different than it is now. Venerable as it is, X is not particularly well-suited to many of the devices or usage scenarios that predominate today.

So by implementing Mir, an entirely new display server that Canonical is building from the ground up, Ubuntu developers are doing something radically different. They're bringing a crucial part of the open source ecosystem into the modern age, creating a display system tailored to work well on the types of hardware—especially phones and tablets—that will define the future.

^{Sources:Ubuntu Wiki & Mir for Ubuntu Linux}