AlphaMod, BlendMode


I’ve tried playing a little with BlendModes and AlphaMods.
I discovered that setting an AlphaMod which is little enough
(let’s say, 100), the objects had a nice “blur” effect (trail ?)
when moving.
I’m new to all this, what are blend modes and alpha mods,
and what are they used for ?
I’ve seen one can achieve nice palette effects with them, but
maybe there is another purpose ?