Chess Clocks

For what purpose and how a chess player uses a chess clock in the game of chess? 
 
A chess clock is used just to give each player the exact time they have to play their moves. A use of a chess clock in tournament play is an attempt to stop players from taking irrationally long period of time to make their moves which may affect smooth progress of the game or even disrupt the whole tournament schedule.

In playing with a chess clock, each player has their own clock, one clock for each player and it is set to the time agreed for the game. The game’s time control is a set amount of time each player has for the whole game or a set amount of time plus certain seconds per move this can be different depending on the tournament or match. 
 
The player making the first move press his clock and release his opponent’s clock. After a move is made, the player press his clock again and release his opponent’s clock. The game goes like this until one makes a move then he will start then press his clock; so that each has a chance to play.

If a player runs out of time, that person loses the game; this is known as a time forfeit. A certain number of seconds may be added to the clock of those participating in some tournaments or matches before they move (delay time) so they will not run out of time early. 
 
To sum it up, chess clocks are used during chess tournaments to monitor and control the amount of time each player has for their moves preventing players from taking too much time and disrupting the tournament schedule. In using a chess clock, both players will have their own clock and there will be a set time control, then the one who makes the first move starts his/her clock and stops his/her opponent's clock. The game proceeds with each player making a move and then starting their opponent's clock, if a player runs out of time they lose the game.