Simultaneous exhibition

A simultaneous exhibition or simultaneous display is a board game exhibition (commonly chess or Go) in which one player (typically of high rank, such as a grandmaster or dan-level player) plays multiple games at a time with a number of other players. Such an exhibition is often referred to simply as a "simul".
Procedure.
In a regular simul, no chess clocks are used (if they are involved it is called a "clock simul"). The boards are usually arranged in a large circle or square and the exhibitor walks from board to board in a fixed order. Each individual participant is expected to make a move when the exhibitor arrives at his/her board. The exhibitor may pause briefly before playing his/her move, but will typically attempt to avoid lengthy pauses because too many such pauses will cause the exhibition to continue for an extended period. Longer exhibitions increase the risk of fatigue-induced blunders on the part of the exhibitor, especially since the individual participants remaining at the end tend to be the stronger players who represent the exhibitor's most challenging opponents. As games are finished off, they are usually not replaced and only a few games will remain in progress at the end of the exhibition. At this point clocks are sometimes introduced with each side getting a fixed amount of time. In most regular simuls, the exhibitor plays White in all the games and the individual participants are of varying playing strengths (though they are typically below master class).
In clock simuls all the games are played as normal tournament games and are timed by a chess clock. These simuls require the exhibitor to accept a substantial time handicap since his/her clock continues to run on all boards. These simuls typically involve a relatively small number of individual participants whose playing strength is at or near master class. Occasionally, grandmasters have given blindfold simultaneous displays. In such displays, the exhibitor does not look at any of the boards, but retains all the moves of the games in his/her head. The opponents utilize boards and pieces in the standard fashion, but their moves are communicated verbally to the exhibitor by an arbiter or intermediary.
Donner's advice.
Dutch Grandmaster Jan Hein Donner offered the following advice to a player taking a board at a simultaneous exhibition:
If you are to stand a chance of scoring a half or a full point, there are a few things to bear in mind:
Games.
Here are some significant games from simultaneous exhibitions:
Internet-based simultaneous exhibitions.
The internet has allowed for the creation of chess game services wherein people may play an opponent from anywhere in the world. Popular sites such as Lichess may have many thousands of active online games as well as tens of thousands of viewers during any time of day around the world. This new online chess paradigm allows for world class players to be actively playing chess as well as teaching and giving demonstrations. On 13 April 2019, a simultaneous exhibition was hosted by Lichess for International Master Marc Esserman who engaged 100 players. He rapidly moved through a hundred Kings Pawn E4 opening and the matches lasted anywhere from thirty minutes to a full eight hours. Many top level players were involved and the exhibition lasted for just over eight hours. IM Marc Esserman won 82 of the games played with 11 ending in a draw.
Tandem simul.
A less popular variation of simultaneous exhibition is the tandem simultaneous exhibition, also known as leapfrog simultaneous exhibition, where more than one (usually two) experts play a number of opponents, making successive moves without consulting one another.