Even and odd functions are similar, but they also have their differences. They're similar in the fact that the both are reflective but they differ in the way that they reflect. Even functions reflect over the y-axis so that they have y-axis symmetry. Odd functions reflect over both the x-axis and y-axis, so that they have x-axis and y-axis symmetry. To check an even function you have to find out if f(x)= f(-x). To check an odd function you have to find out if f(-x)= f(x). Some families of functions will always be even or odd. For example; a quadratic function will always be even, and a cubic function will always be odd.