I've seen this term mentioned quite a few times lately as more being a good thing, as in some particular wheel/ tire combo having more pneumatic trail and therefore being superior. But it's thrown around as if everybody should know what it is without further explanation. Am I right in thinking it has to do with overall tire diameter bring made up of more volume and less rim diameter as opposed to the other way round?

And how do these almost identical overall diameters relate in terms of trail/ pneumatic trail:
23x622
42x585
55x559

Is more better? Is there a limit where more negatively affects handling?
In layman's terms please

Thanks.