An even function is a function for which the value of $f(\text{-}x)$ is equal to the value of $f(x)$ for all the values in its domain. That is, opposite inputs have the same output. The graph of an even function is symmetric about the $y\text{-}$axis. The functions $y=x^2$ and $y=2|x|$ are two examples of even functions. Notice that if a function is even and the point $(x,y)$ is on the graph, then the point $(\text{-}x,y)$ is also on the graph. A function can be even, odd, or neither.