Question

What is domain?

Answer 1

if a function of a variable exists, then that variable has a set of numbers if can be. This set (for the variable) is called the domain of the variable. The set of the function itself is called the range of the function.

example
y=x^2-1 for all x.
The domain of x is all real numbers.
The range of y is from -1 to infinity

Answer 2

Also a part in a system in which living organisms are classified.