What is tube rolling?

While others have clearly defined tube rolling, I would like to add the benefit of NOS tubes. The difference in sound quality you will experience is astounding. Unfortunately this may be somewhat design dependant and not 100%. I would recomend numerous specific inquiries before spending hard earned cash'

but why is it called "rolling"?

Because tube swapping, tube changing, tube trying, tube experimenting all sound lame.
What would you call it?

Why is it calling rolling? It's a colloquial term. Why is browsing the world wide web called "surfing"? Don't think about this too hard.

01-20-13: Lupinthe3rd
Don't think about this too hard.

Best advice I've heard in a long time.