and why are they better than what may come in a kit?
I've been looking through a lot of the work in progress photos on this site and have seen repeated references to "etched" parts. What are they and what's the big deal?
They are replacement parts etched in brass (Mostly) and are finer than the pieces that come with the kits. Because of the limitations of the injection moulding process plastic parts are often cast thicker than they should be and people like to replace them with photo etched parts. You can see an example here
http://www.missing-lynx.com/reviews/ger ... r35103.htm