So here on the left, you see that this curve looks just like y equals x squared until we get to x equals three, and instead of it being three squared, at this point, you have this opening, and instead, the function at three is defined at four, but then it keeps going, and it looks just like y equals x squared. This is known as a point or a removable discontinuity, and it's called that for obvious reasons. You're discontinuous at that point. You might imagine of defining or redefining the function at that point, so it is continuous, so the discontinuity is removable, but then how does this relate to our definition of continuity? Well, let's remind ourselves our definition of continuity. We say f is continuous, continuous, if and only if, or let me write f continuous at x equals c, if and only if the limit as x approaches c of f of x is equal to the actual value of the function when x is equal to c. So why does this one fail? Well, the two-sided limit actually exists.