A lock is a mechanical or
electronic fastening device
that is released by a physical
object such as key or secret
information such as a key code
or password, or combination of
more than one of these. A
combination lock is a type of
lock in which a sequence of
numbers or symbols is used to
open the lock. The sequence
may be entered using a single
rotating dial which interacts
with several discs or cams, by
using a set of several
rotating discs with inscribed
numerals which directly
interact with locking
mechanism. Padlocks are
portable locks used to defend
against theft, vandalism,
sabotage, unauthorized use,
and even harm. They are
designed to protect against
some degree of forced and
surreptitious entry.
