 Game play is a dynamic process, where players repeatedly obtain new information about other players. Certain aspects of information collection are hard-wired into the game’s structure, such as observing moves, or, in settings of imperfect observation, changing from one information state to another. Other updates may be extraneous, such as signals about the type of opponent one is dealing with. As of now, there is no general logical theory encompassing all these phenomena. Yet, instructive samples exist. The first topic to address concerns the players’ knowledge, the second their belief.