I have been tasked with setting up a QA program for large amounts of
data. I have a lot of experience with Excel but none with VBA and I
know that conditional formatting cannot be done with a formula.

Simple example:

Cell A1 = 100
Cell A2 = 180

Wanted outcome:

IF(ABS(A1-A2)<100,"MAKE THE CELL RED","MAKE THE CELL GREEN")
IF(ABS(A2-A3)<100...ETC.

I need to loop this situation through the entire spreadsheet, which
over the course of time will have a variable amount of rows (could be
upwards of 50,000).

Honestly, I don't even know where to start to write the first line of
code. I played around with some commands, but nothing really made
sense to me.

Thanks for any help you may provide!

Douglas