In this chapter we give the full description of the discrete variational derivative method. We ¯rst de¯ne discrete symbols and formulas required to describe the method. Then we present concrete and rigorous procedures of the method for each of the target PDEs introduced in Chapter 2 in turn. Readers can refer to Chapter 4 as needs arise, where many concrete examples that are useful for understanding the method are given. In the end of this chapter, a brief explanation on discrete functional analysis is given, which will be used in the subsequent chapters.