Some board games, such as chess and Go, use an adjournment mechanism to suspend the game in progress, or at least did so before the advent of computer programs that play that game better than any human. The rationale is that games often extend in duration beyond what is reasonable for a single session of play. Adjourning the game would allow it to be continued at another time, typically the following day. There may be a sealed move: the next move that would be made is sealed in an envelope, to be played out when the game resumes (normally played by the director or arbiter). This practice ensures that neither player knows what the board position will be when it is their next turn to move.