What are the files categories according to the format? Give a brief description

We can classify files in:

ASCII:
       They are file that consists of ASCII characters. You can view them in a text editor like notepad . When you store the character "a", in fact, you are storing the ascii value, the number 61.

BINARY: 
       They are files that store a secuence of bits ( 0's and 1's). They are intended to be interpreted as something other than text characters.