Question

What is the definition of “i”? What do we use it for?

Answer 1

i means Iota.
Its an imaginary number.

Answer 2

i is a complex number which is equal to underoot(-1)

Answer 3

strictly speaking i is not a complex number - it is an imaginary number

a complex numbe is made up of real and imaginary parts such as

a +ib

Answer 4

Here are a few values of "i"?
i = \[\sqrt-1\]
i^2 = -1

Answer 5

@MrNood Agreed

Answer 6

Thank you everyone!!!

Answer 7

For various uses see
https://en.wikipedia.org/wiki/Complex_number