In a parliamentary government, a shadow cabinet is a group of advisors appointed by the party that's not in power. Though they don't have real authority, the shadow cabinet can sometimes influence policy.
The shadow cabinet is an official part of the United Kingdom's political system, in which an entire alternate cabinet is formed by the opposition party, which mirrors — or shadows — the actions of the official cabinet. This group keeps a close eye on decisions made by the ruling party and often suggests alternatives. These "shadow ministers" are also ready to jump into positions of authority if their party regains power in an election.