While hunting for information to demystify the distinctions between the newD4 and D800 cameras, I came across this extremely useful set of tutorials from Cambridge in Colour.
I can be particularly "thick" at times, probably a product of the myriad of brain cells I've killed off in my lifetime, but I (almost) managed to understand the relationship between sensor size, pixel density and in one of the Cambridge tutorials. Go figure.
Bottom line: I thought I should share the link with everyone else here at AP. As great as our Library and tutorials are, sometimes you need it worded or presented another way before it sinks in. I know I do. Enjoy!