The Formations :
There are 11 players on a team and there are several commonly used ways to arrange them to play on field. The formations means how the players in a team are positioned the pitch. Though different formations can be used according to teams wish, how they want to play, attacking or defensive football.
Formations are described by categorising the players (not including the goalkeeper) according to their positioning along (not across) the pitch, with the more defensive players given first. For example, 4–4–2 means -four defenders, -four midfielders, and -two forwards.
Traditionally those within the same category (for example the 4 midfielders in 4–4–2) would generally play as a fairly flat line across the pitch, with those out wide often playing in a slightly more advanced position. In many modern formations this is not the case, which has led to some analysts splitting the categories in two separate bands, leading to four or even five numbered formations. A common example is 4–2–1–3, where the midfielders are split into two defensive and one offensive player; as such this formation can be considered a kind of 4–3–3. The numbering system was not present until the 4–2–4 system was developed in the 1950s(according to wiki).The two most commonly used formations today are probably the 4-5-1, 4-3-3, and the 4-4-2 (Note: first # is the # of defenders, the second midfielders, and third forwards) although there are some different variations of each. Two variation of a 4-4-2 are the "flat back four" and a "diamond back" or "sweeper, stopper" where the back four defenders form a diamond with the stopper ahead of the sweeper. Other less commonly used formations are the 3-6-1, 4-2-4, and the 3-5-2.Changes can be made in the formations according to the position of the game. If one team has scored only single goal ,they can change formations in the closing stages of the match or they can put more players forward to score more goals when they are trailing by a goal.
Narrow formations :
Teams with a surfeit of central midfielders, or teams who attack best through the centre, may choose to adopt narrow formations such as the 4–1–2–1–2 or the 4–3–2–1 which allow teams to field up to four or five central midfielders in the team. Narrow formations however depend on the full-backs (the flank players in the "4") to provide width and to advance upfield as frequently as possible to supplement the attack in wide areas.
Wide formations :
Teams with a surfeit of forwards and wingers may choose to adopt formations such as 4–2–3–1, 3–5–2 and 4–3–3, which commit forwards and wingers high up the pitch. Wide formations allow the attacking team to stretch play and cause the defending team to cover more ground.
Teams may change formations during a game to aid their cause:
Change to attacking formations :
When chasing a game for a desirable result, teams tend to sacrifice a defensive player or a midfield player for a forward in order to chase a result. An example of such a change is a change from 4–5–1 to 4–4–2, 3–5–2 to 3–4–3, or even 5–3–2 to 4–3–3.
Change to defensive formations :
When a team is in the lead, or wishes to protect the scoreline of a game, the coach may choose to revert to a more defensive structure by removing a forward for a more defensive player. The extra player in defence or midfield adds solidity by giving the team more legs to chase opponents and recover possession. An example of such a change is a change from 4–4–2 to 5–3–2, 3–5–2 to 4–5–1, or even 4–4–2 to 5–4–1.