Printing and Finishing - The Graphic Design: Reference and Specification - page 146

Scoring: To facilitate folding, a crease is
applied using the metal edge of either a
rule or a wheel so that an embossed ridge
on the paper is formed. Heavy text and
cover stocks should always be scored.
Scoring is especially important to prevent
cracked ink on fold lines when using coat-
ed stocks with heavy ink coverage.

Perforating: Perforating involves punching
a line of holes to make tearing easier.
It can be done as part of the binding
process to make signatures easier to
fold before they are bound and trimmed
as part of a publication or as a means of
facilitating tear-offs on pieces that include
response vehicles, such as business reply
cards.

Drilling/punching: Pieces that are ring or
post bound require holes ranging between
1 ⁄ 8 " and 1 ⁄ 4 ". Commercial printers and
binderies use a drill to make these holes
according to size and placement specifi-
cations. Spiral and plastic comb binding
require punching holes, a process that
costs a bit more than drilling.

When a piece is scored, the fold should always be made
with the ridge or hinge on the inside for minimum stretch.