This image is a custom colored version of a cloud procedural texture with a cell noise basis. What that means is that the procedural texture is made and written mainly for creating clouds or texturing them, either by deformation of a shape or just using color, or both. The basis is how the texture will be made, or put together. There are many options in Blender regarding basis, but this one is cool for a few reasons.
   I've been a fan of this kind of pattern for a long time, but I've always had to make a block grid on Office and add random transparency values (1 by 1) and that took ages and never looked this good, so it's more efficient.
   Secondly it looks really great and gives you unlimited detail, because it's mathematically produced, like vector graphics.

If you want to work with these free and flexible texture systems built into Blender, then get my book when it comes out!
(^^,)
It's not just for advanced users and even beginners can benefit a lot from it, learning what tips and tricks there are to getting the result you want and a few tutorials for Cycles Render and a few for Blender Render.

Thank you for reading!

Thank YOU!!!!!!!!!