1. The **range** of a function is the set of all possible output values (or $y$-values) that the function can produce. 2. More simply, when you input all the allowed $x$-values (the domain) into the function, the range is what you get out. 3. For example, if $f(x) = x^2$, the domain is all real numbers, but the range is all real numbers greater than or equal to zero because squares are never negative. 4. To find the range of any function, analyze the function's formula or graph to see what values $y$ can take.