The game of rugby is broken into two 40-minute segments with a five minute break in between. The ball looks a little like a football, but it's larger, typically more colorful and slightly more oval. The only timeouts in rugby are called for injuries. If a player is injured, he has 60 seconds to recover or leave the field. During the course of a game, teams are allowed to replace up to four injured players.
Play officially begins with a kick-off at the 50-meter line. A player in possession of the ball can run, kick the ball forward, or pass the ball to another player running behind him or to his left or right (laterally).
It's against the rules to pass the ball forward in rugby. It's also against the rules to protect or shield the ball carrier. (These are two major ways in which rugby and football differ.) Once the player with the ball is tackled, the ball is released and can be taken up by any player on either team. The convergence of players using only their feet to try and recover or steal a downed ball after a tackle is called a "ruck." It's one of the most common formations in the game. If a stopped ball never touches the ground, both teams can try for possession using a formation called a "maul" in which at least three opposing players use their hands (not their feet) to try and take the ball from the ball carrier.
A scrimmage (or scrum) is the method used to restart play after a rule infringement (penalty). In a scrum, the forwards from each team take opposing sides and squat shoulder-to-shoulder in three rows, heads interlocking at the spot where the infringement occurred. The scrumhalf not responsible for the infringement throws the ball down the lane created between the opposing teams' legs (the tunnel). The objective for each team is to hook the ball using only their legs and pull it back into their territory. To restart the match after a ball goes out of bounds, a lineout is thrown to the team not responsible for the out-of-bounds play.
To win the game, players have to score. So, let's move on to the specifics of how to score points and win a rugby match.