If a referee announces a goal before the ball crosses the goal line completely, play is resumed with a dropped ball. The winning team is the one that scores the most goals. The match is drawn if neither team scores any goals or scores an equal amount of goals.
In soccer, a goal is scored when the opposing goalkeeper fails to stop the ball going in between the goal posts. If the goalkeeper does make a save, the ball may not cross the line completely and a goal may not be awarded. If the ball hits the post on its way into the goal, the goal is called "wide". If the goalkeeper catches the ball with their hands, it is considered a handball violation and can lead to a penalty kick being taken by the scoring team.
A goal can be scored directly from a free kick or after creating chances through dribbling, passing, shooting, etc. without actually taking a free kick. This type of goal is known as a "scoring chance" and is usually marked with a red card. It is possible for a player to score a goal by deliberately kicking the ball past the goalkeeper using their foot (for example, when playing keepie-uppy). However, this type of action would normally result in a foul being committed by the player doing the kicking and they would therefore lose possession of the ball.
If a throw-in results in a goal, the referee will not award a goal to either team and will instead restart the game with a goal kick or corner kick. This usually occurs when a player from the opposing team catches the ball after it has been thrown in.
In professional soccer, if a throw-in results in a goal, the referee may choose to call a foul on the throwing team and give the other team a free kick. He/she will then tell both teams to return to their respective sides of the field before continuing with the game.
In lower league soccer, if a throw-in results in a goal, the referee may simply whistle for a new ball instead of calling a foul. The original ball is then taken by the opposing team and played towards the opposing penalty box until it is kicked away by a player who has not been touched by an opponent. If this happens twice within the game, the referee may decide to replace it with a 7th vial ball.
In international matches, if a throw-in results in a goal, the referee may choose to call a foul on the throwing team and give the other team a free kick.
If a dropped ball approaches the goal without being touched by at least two players, the game is resumed with a goal kick if it penetrates the opposing goal. If the ball penetrates the team's goal, it is awarded a corner kick. If the ball goes directly into the opposition's goal from a corner kick, the referee has no choice but to call "time." This happens very rarely but does happen when a goalkeeper misses their catch - think of Peter Schmeichel missing his attempt against Diego Maradona in the 1986 World Cup final.
In fact, it was during this match that he became world-famous after saving a penalty shot with his chest while lying on the ground. The German public loved it and he became one of the country's most popular athletes at the time.
Corner kicks are important because they give teams the opportunity to start attacks from close range. With only 10 men behind the ball, coaches will often tell their players to head the ball whenever it drops so it can be retaken quickly.
Direct corners are rare but when they do occur it's usually because the goalkeeper missed their catch. So whenever there is any doubt whether or not the ball went into the net, immediately stop playing and wait for the referees decision before continuing with the rest of the game.