Polyurethane on wood floors -- What is this "wet edge"?

proofer

I'm going to polyurethane my wood floors tomorrow. What is this "wet edge" that they keep talking about? Also, what's the best thing to apply polyurethane with---brush? rag? mop on a stick? wools lamb? stain brush? The product is Minwax, and I believe it's oil-based; it's called Minwax Polyurethane Floors. Also, what is a T-bar?

jason h

as you apply the poly do not let the edge dry out or you will always have a ridge that you can see in the finish. i have good luck with a 1/4 inch nap roller. throw away after each use. light sand and damp cloth clean between coats. always use a GOOD quality finish or you will redo often