Is a Playfair cipher a substitution cipher or a transpositio

Is a Playfair cipher a substitution cipher or a transposition cipher? What type of cipher could you use in combination with a Playfair cipher to make it more difficult to break?

Solution

Playfair Cipher is a sustitution Cipher. Playfair is diagraph substitution cipher which uses 5x5 matrix, in which the key word is written first and the remaining blocks of the matrix are filled with other alphabets. In cryptography, confusion and diffusion plays a prominant role in the development of a cipher. Confusion makes the relation between the key and ciphertext as difficult as possible and it is achieved by combining the transposition cipher with the Playfair cipher.