Sweeper / Libero The sweeper or “libero” must always be "the last player" in defense (after the goalkeeper, of course).  Their job is to close down gaps left by other defenders.  The sweeper/libero roams laterally, a few yards/meters behind the last line of fullbacks.  They must try not to sway too far towards the flanks.  The sweeper analyzes the development of plays, anticipates where open angles and passing lanes are forming and make quick decisions about dealing with them. Because they never mark enemy attackers, sweepers can move a great deal forward when their team is in possession of the ball.  This frequently finds the enemy defense unprepared as an unmarked player is unexpectedly introduced to the play.  Overall, the sweeper should be very perceptive (usually experienced) with good ball handling skills and confidence. Stopper / Center fullback The stopper is the center player in a defensive line.  Some teams may use two stoppers in conjunction.  Their main task is to mark the most advanced enemy forwards and fight with them in 50/50 encounters.  This is the most defensively-oriented field position in soccer. Stoppers have to remain in the backline, almost at all times and usually cover the shortest distance in a match (second only to goalkeepers).  Stoppers rarely get involved in offense, except in set pieces like corners and during initial buildup.  Playing in the middle of a defensive line means having the ball served in your area from various directions and at variable heights. Dealing with such situations requires aggressiveness, strength, speed, good heading ability and courageousness in one-on-one battles. Fullback Fullbacks are the defenders positioned on each side of the stopper.  They cover the space along the entire flank and therefore must be fairly quick.  In defense, the fullback usually marks an enemy forward or covers his flank, awaiting incoming enemy wingers.  Fullbacks get actively involved in their team's offense by staying wide, making overlapping runs and pushing up the flank.  In modern football, it is not uncommon for a free (not marking) fullback to move up the wing and take the position of a winger thus spreading the enemy defense apart.  To do this job, fullbacks need to have good speed and stamina. Outside midfielder The outside midfielder must be very fit and is supposed to be active in both defense and offense.  In defense, they must mark the widest opponent on his flank.  When they find themselves free, the outside midfielder may pinch in towards the middle while remaining on the same level with the ball.  This way, they are preserving the defensive compactness of his team.  In attack, the outside midfielder must stay wide, especially in the early stages of buildup.  By providing width, they will stretch out the enemy defense.  The outside midfielder should make supporting runs up the sideline and should be able to carry the ball.  Besides good stamina the winger must also possess good one-versus-one skills. Winger Even although the classical winger who dribbles up the sideline is nowadays being replaced by an all-purpose outside midfielder, the "old" winger position is still present in many teams today.  Wingers are commonly found in teams who play with three attackers.  The definition of a winger is not quite universal and it is not uncommon to refer to an outside midfielder as a winger.  Traditionally, wingers are strictly attacking players who stay wide, dribble the ball forward and serve in crosses. Defensive midfielder The defensive midfielder is the backbone of the team.  Their job is similar to that of the sweeper with the exception that they operate in front of the defense, between the offensive midfielders and the stopper.  They roam laterally from sideline to sideline, usually pressuring the ball.  If any of their teammates gets beaten in the middle of the field, the defensive midfielder is expected to be first in providing backup.  In offense, the defensive midfielder must stay behind the attacking line, collecting rebounds and miss-kicks.  They are also expected to make supporting runs and give back pass options, especially when the ball is out, near the sideline. Center / Attacking / Offensive midfielder Offensive midfielders are usually the fittest players in a team, considering that they have to be involved in almost every attacking play.  Apart from their top form, midfielders need to have good technical ability.  When a skillful midfielder is dribbling, they are not supposed to look at his feet, but should be scanning the field for open space and moving teammates.  In a practical sense, the midfielder needs to possess enough skill so that they can concentrate on his primary job of distributing the ball without worrying about the mechanics involved.  Overall, the job requires skill, stamina as well as vision and tactical understanding.  When their team does not have possession, the center midfielder is expected to drop back and pressure the ball. In offense the attacking midfielder should be in involved in the action by making runs towards the ball.  Even before they get it, they should already know where and how they want to distribute it.  Offensive midfielders who are very active in directing their team's attacks are often given the title "playmakers".  Playmakers need to be fed a lot of passes in order to coordinate the offensive movement of their team. Striker The main ability of this player must be their strength and heading.  Their job is simple: to stay in front of the enemy goal, attract enemy defenders and score.  Unlike the typical forward, the striker doesn’t shift to the sides as much.  They stay in the middle as a target player and will typically be marked by at least one player.  On attacks, they may try checking to the ball and shielding or laying it off, but he'll usually stay with the last enemy defender.  The striker's defensive duties are to pressures the opposing defenders while they are initiating an attack. Forward The job of the forward is not merely to head for goal every time they receive the ball.  They must also make runs towards his own goal and support the midfield rather than simply rush forward.  This can best be observed by watching top level games, where forwards are often playing with their back turned to the enemy goal.  Whenever a team is playing with two forwards, they must both move in conjunction.  If the ball is on the left flank for example, they must shift towards it so that one of them is in the center and the other near the sideline. By keeping the distance between each other constant, forwards can work the ball effectively while pulling apart the enemy defense. Since forwards usually work under a lot of enemy pressure, they need pace and quick ball handling skills.