I feel like I should've read this somewhere or sometime, and I probably did, but when you're taking readings, what's the difference between "apparent" values and "real" values? And what causes the difference?
What type of readings? Specific gravity. If so they are probably talking about adjusting for temp. Hydrometers are set at 60F i think. There are conversion tables around that will give you a true reading based on the temp of your wort when you take your reading.