The term curve fitting is more general than regression . Your approach to curve fitting depends on your goal. In some circumstances, your goal is simple. You don't care about models, and don't expect best-fit values that you can interpret. Instead, you just want to draw a smooth curve to make a graph look attractive, or to use as a standard curve.
Prism provides two approaches for fitting a curve without selecting a model.
A cubic spline curve goes through every data point, bending and twisting as needed. A lowess curve follows the trend of the data. Lowess curves can be helpful when the data progresses monotonically, but are less helpful when there are peaks or valleys. Prism lets you choose between fine, medium and course lowess curves. The fine curve reveals the fine structure of the data, but tends to wiggle a lot.