Score fold (aka scoring) is the process of creating a crease in a piece of paper, allowing it to cleanly fold.
A ridge is made into the paper through indent pressure which creates a crease. The fold is then manually applied to the raised side of the ridge.
Score fold
The score ‘ridged’ impression is made on a piece of paper, allowing it to be manually folded.
The fold is then manually applied to the raised side of the ridge.