Why is square root of 2 an irrational number?

The square root of 2 is an irrational number because it cannot be expressed as a ratio or fraction, a/b, where a and b are whole-number integers, and b does not equal zero.

this is true but in simpler terms, it's b/c it's and on-going # just like pi (3.14.... and so on) and it goes on forever so there is no square root, so it is irrational.