Quick question about DirectX 12

I see that DirectX 12 is coming out soon, and if I'm being honest, I'm just wondering what it actually is. I have a GTX 970, and according to the NVIDIA website, my card is supposed to support this feature. I guess I'm just curious about what its actual purpose is. Thanks.

In short: it’s a standardized library of routines for math, rendering, animation, video, and audio. Every new version rolls out faster, better, and more complex instructions designed to squeeze every bit of performance out of low-level machine language. "Standardized" means it's hardware-agnostic—any piece of gear that wants to be DirectX 12 compatible has to be able to execute everything in that library.

But for a program or game to actually use those instructions, they have to be baked into the code itself. So, if a game was built specifically for the DirectX 11 instruction set, it won't run on DirectX 12 until the devs actually go in and implement the new commands into the software...