The details panel
This is just like any other details panel you could find around the different editors of the Engine. And as is the habit with all other Unreal Editors, by default, if you are not selecting any of the emitters inside the emitters list area, this panel will display the overall properties for the particle system itself.
But, as a sensitive window, it will automatically change its content and its set of options and parameters, based on your selection. Go ahead and try to select the emitter itself to see what it can display, or even try to select between the different modules, and you'll notice that it always changes its content and shows you different settings and parameters. Here is exactly where the majority of the magic happens. That is, adding the correct module for the required situation is the trick, but it is trickier when it comes to setting the parameters of the module itself:
Now, after understanding how the details panel works, let's start to breakdown all the parameters...