Since the first release of Ultra Fractal in 1998, the formulas written for it have become larger and more complex. Even though many formulas are quite similar, they could not share any common code, but had to be written as stand-alone formulas. For example, if you wanted to add just one new feature to an existing formula written by someone else, you had to create a new formula, duplicate all the code from the original formula, and only then add some new things.
To improve this situation, Ultra Fractal 5 introduced the ability for formulas to re-use common code via plug-ins. You can view a plug-in as a "black box" that adds functionality to a formula. Via plug-in parameters, a formula enables you to select the actual plug-in that performs an action for the formula.
The formula declares what kind of functionality it needs and you can select any compatible plug-in to actually implement it. This makes it possible for formula authors to write a new plug-in to implement just the new feature that they want to add to an existing formula. The formula doesn't have to be changed at all. You just select the new plug-in when you use the formula.
For everyday users, plug-ins make it possible to combine existing elements in new ways without needing to do any programming. For formula authors, plug-ins make it easier to write and manage complex formulas.
Next: Example 1 - Formula plug-ins