Is there any way, if given multiple points and you wanted to find the equation of the graph where these points lie, how would you find out: First off equation is it? Line, Parabola, Hyperbola, etc? Second, how do you find the equation of this graph?
For example if we are given the points (1,1) (2,4) (3,9) (4,16) and (5,25) how do you find the equation of this graph?
This problem is related to interpolation. One of the big problems is that there are infinitely many functions that go through a set of points, even the points (which seem to 'obviously' lie on a parabola) that you gave us.
One of the most naive types of interpolation is to use Lagrangian polynomial interpolation (mentioned in the link above). It would give a quartic polynomial that goes through those points above. But that is not at all unique.
A bigger problem is that often, it's not clear what makes a certain interpolation any 'simpler' than another. This is a very extensive area of study. For more, look at the polynomial interpolation page.