The identity function is a special linear function. The domain and range are the set of all real numbers. Its graph is a line whose slope is 1 and whose y-intercept is 0.

It is an odd function and is increasing on the entire interval.

The graph intersects the x-axis and y-axis at (0,0).

Important anchor point coordinates are:
(0,0) (-1,-1) and (1,1).

You can graph many variations of the identity function using transformations. Check out an example that applies several transformations to the basic identity function.