You will found two types of chess clocks such as the traditional clock and Fischer-clock. There are two time counters in the traditional chess clock and one for each player. It is compulsory to push a button after a player makes his move and then the opposition is allowed to start his counter. In fact these practices prolonged until the finish of the game. In analog clocks the process makes easy for the players to make their moves without waiting oppositions move. In happens like a flag will fall if time is over for one player, while a digital clock will beep to indicate the time is getting over.

The same way also can be found in the Fischer-clock like you found in analog or digital clocks. The name of this clock is derived from the name of Robert Fischer a former World Champion Grandmaster. You will find a little bit extra time to think about your move because a constant amount of time likely 5 or 10 seconds is added after your every move made. In fact this extra time will help to prevent players from running into time-trouble.

Time controls may differ from game to game in the tournaments. The chess clocks are fits with the concern time controls are very significantly used. The time is announced before the start of the game according to that the players need to adjust with that time. For instance: 'two hours for the whole game', 'one and half an hour for the first 40 moves and one hour for the rest', 'two hours for the first 40 moves and half an hour for every 20 moves thereafter', 'one hour and 15-seconds-added-per-move for the whole game etc are some time control announced at the tournament before the game scheduled to start.