More advanced substitution ciphers use two or more alphabets, and are referred to as substitutions.

More advaced substitution ciphers use two or more alphabets, and are referred to as polyalphabetic substitution. In this kind of substitution, multiple alphabet ciphers are being used. To facilitate encryption, all the alphabets are usually written out in a large table, traditionally called tableu. 

What's the rest of it? lol

These are very for instance for math pemdas parenthesis, exponents, multiplication, division, addition, subtraction without that i would never be able to remember what to do first with it i can remember.