To play pool, one of the most popular games around the world, you essentially need 3 things -  a pool table (preferably green, or even the modern day blue), a cue-stick of varying dimensions, a white cueball on the table and at least one other ball, called the object ball for you to aim the cueball at.  There are 6 holes, called pockets, 1 at each corner of the table and 2 located at the middle of the long side of the table.  The objective is simply then, to hit the cueball, such that the object ball will, on collision with the cueball, enter the pocket.   On the other hand, having the cueball enter the pocket is a big no-no, in which case, pool players, for some unknown historical reason, call it a scratch. 

The most common pool game, called 8-ball pool, involves 2 players, with not just one, but 15 object balls.  Each player has 7 balls, either all stripes, numbered 1 to 7, or all solids, numbered 9 to 15.  Each player will then attempt to put all his balls in the pockets, before winning the game by finishing off the number 8 black ball.  The objective sure sounds simple, but playing it need not be so.  The rules of playing 8-ball pool may be a little bit more complicated, and more details can be found readily online.