What Is Domain and Range?
The domain of a function is the complete set of input values (usually x) that the function accepts without breaking a math rule, like dividing by zero or taking the square root of a negative number. The range is the complete set of output values (usually y) the function can actually produce.
Example
For f(x) = √x, the domain is x ≥ 0 (you can't take the square root of a negative number), and the range is y ≥ 0 (a square root is never negative).