Possession in soccer is the able to keep the ball. In order for this to be successful you need to have enough players on the team with a wide range of skills to keep possession.
In order to keep posssession players must have more than the ability to pass the ball. Players need to have desire. A lazy team who does not want to move off the ball to get into position to receive a ball may have a hard time possessing the ball. Players also need the abilty to receive and control the ball well. A well placed pass is great, but if a player cannot control it you've lost possession.
Players also need good vision. You need to see the right play at the right time to keep possession. You need to see the cutters and the open players to solidify control of the ball. And finally you need to be smart. Realize why you have possession at that time. Are you trying to curve up the other teams defense down the field so you can score? Or are you trying to keep possession of the ball because you are up 3-0 and you're trying to work the clock. What ever the reason, have a reason for possession of the ball. SImple control of possession doesn't mean anything, its purposeful possession.
Learn about resting with the ball through possession.
Possession of the ball is the most valuable thing in soccer. You cannot concede goals or be at any threat from the opposition if you manage to retain possession of the ball. Even if you are not penetrating the opposition defensive line, possession of the ball can cause the opposition team problems on a number of levels.
Build from the back possession drill- This possession drill uses nine on offense and six on defense. The objective is to pass the ball seven times before being able to dribble over the midline for a score. For a more in depth explanation read the article Soccer Possession Games.
Circle Possession Drill- Draw three circle, the biggest 30 yards, them middle circle 20 yards and the inner circle 10 yards in diameter. If the coach yells 3 the offense must play within the 30 yards circle. If the coach yells 1 the offense must play within the 10 yard cicle. For a more in depth explanation read the article Soccer Possession Games.