# Definition of diffusion matrix

I've been studying this article and since I'm not studying cryptography in English and it is not my native language, I don't understand some of the terminology. More precisely: what are diffusion matrices as mentioned on page 3 right at the beginning of chapter 2? Do they have something to do with diffusion defined in Shannon's theory?

A diffusion matrix transforms columns and it similar to the MixColumns operation of AES. It is optionally followed by a ShiftRows (like in AES) to provide further mixing where ShiftRows permutes the rows*.