i

You should say that "i" is not number, but this is actually  a number, "i" is the square root of negative number.


This number is deeply connected with complex number. Complex number distributed mathematics new possibility from the world of real numbers.

Also, "i" connect the imaginary number to real number, also this express the 2 dimensional world not using vector.

"i" is not just one thing but include so many possibilities and  potentials.