Think of it as a very small audience. Say over all, widgets have a following of #*$!#*$!x. Maybe "everyone" likes widgets. And everybody sell widgets - but only in red and green.
Those interested in "only" blue widgets - well there are only #*$! of those customers. Not nearly as many, but if you offer the blue widget, you have loyal customers as the blue widget can be hard to find.

that made so much sense :o

i would assume that a microniche is just another way of saying:
a very small niche

Or a niche within a niche. Think of "widgets" as the primary niche. Think of "green widgets with lace trim" as a microniche.

That may not be correct but I thought it sounded good.