what is Substance???

Hi with the new release of 3.4 unity and some new demo i kept on seeing people talking about a feature called Substance. So after some wiki search i could not find an answer. Can anybody explain to me what Substance means in the context of Unity3d?

Here is your answer :

http://unity3d.com/unity/engine/substances

Substances are basically textures and filters that can be modified in real time using custom parameters to create variations or modify existing textures. Also these textures weight only a few kilobytes.