What is ''mod" ?Is it a kind of remainder?Why or why not?

Answer 1

Yes, the modulo operation or "mod" is related to the remainder. a mod b yields the remainder when a is divided by b.

Answer 2

It is short form of modular function. When a is divided by b and the remainder is n, then n is called a mod b.

Example:

Pi = 22/7 = 3 and remainder 1. Hence 22 mod 7 is 1.
9 divided by 3 = 3 and remainder 0. Hence 9 mod 3 is 0.
1 divided by 7 = 0 and remainder 1. Hence 1 mod 7 is 1.