Perfect information in game theory is when a player who is about to make his move in a game can see all the moves that have been made before.
Chess is an example of a game with perfect information as all the moves are visible to both players. Nearly all card games are games with imperfect information as one player cannot see the other players cards. There are a few card games which do have perfect information. Here are a couple of examples:
Both of these games are two player games where all the cards are dealt out initially. This means that you see all your cards and know that your opponent has all the cards that you don’t have, so you start the game with perfect information about which player has which cards. As the game is played all the moves are seen by both players so they are games of perfect information.
Any game with simultaneous moves cannot be a game of perfect information. This is because when you are making your move you cannot know what move you opponent is going to make at the same time. As you don’t know their move you do not have perfect information about the game.
Most real-life business situations are games of imperfect information as you will not know what moves your opponents are making.