Formation and a meticulous tactical approach to the game are what separates professional football from its amateur version. A team’s formation is the focal point of various tactics employed by the manager during a game and often indicates the team's style of play - attack-minded or defensive.While most top managers are widely regarded for their use of a particular formation, that also depends on the type of players at their disposal.Football formations have witnessed radical changes over the years, in accordance with the changing demands of the times. Back in the 1880s, the most popular formation was the 2-3-5, which would lead to a flurry of goals. More than a century later, this formation is rarely employed, even in the amateur game.On that note, let's take a look at the five most popular formations in football.#5 The 3-5-2 formationChelsea vs Manchester United - The Emirates FA Cup FinalAntonio Conte is a famous proponent of the 3-5-2 formation, which can also be modified into a 5-3-2 one to provide more defensive cover.Inter Milan have achieved great success this season under Conte with the use of this formation. Thomas Tuchel’s Chelsea have adopted this formation too and can attribute their change in fortunes since Lampard’s departure to the effective usage of the 3-5-2.The 3-5-2 comprises three closely-knit central defenders and two wingbacks, who operate in the dual role of a winger and a full-back. The midfield, at most times, contains two holding midfielders to support the defence; in attack, there are three offensive-minded players.This formation provides immense defensive cover, as it has three defenders and two holding midfielders, allowing the players around them to pounce on any counter-attacking opportunities.2010-11: Juventus finish 7th*Antonio Conte takes over*2011-12: Juventus win Serie A 🏆2015-16: Chelsea finish 10th*Conte takes over*2016-17: Chelsea win Premier League 🏆2018-19: Inter finish 4th*Conte takes over*2020-21: Inter win Serie A, ending Juve’s streak of 9 🏆 pic.twitter.com/9t2njg850d— B/R Football (@brfootball) May 3, 2021The effectiveness of the 3-5-2 formation in attack was observed in the first half of Chelsea’s Champions League semi-final first-leg against Real Madrid.The presence of the wingbacks, along with a midfielder and two forwards, allows teams employing the 3-5-2 to outman the opposition defence.#4 The 4-1-4-1 formationLeeds United vs Charlton Athletic - Sky Bet ChampionshipNext, we have the 4-1-4-1 formation, which yielded great success for Germany in their victorious 2014 World Cup-winning campaign.Leeds United have impressed fans and pundits alike in their first season back in England’s top tier. That's largely down to Marcelo Bielsa’s proficient usage of the 4-1-4-1 formation.This formation lays a lot of emphasis on offence but without necessarily compromising defensive integrity. The use of four midfielders makes it much easier to initiate a high press, as the team can make the press a tight, compact unit.The holding midfielder allows the upfield players more freedom to contribute in attacking scenarios; the presence of a wide midfielder/winger with a full-back helps to snuff out opposition attacks from the wings. However, the primary emphasis of the 4-1-4-1 is to outscore the opposition.One of the best ways this formation is employed in attack is by crowding the wings, thanks to a wide midfielder and a full-back, which allows the supporting midfielder to make a foray into the attacking third.Here’s the Marcelo Bielsa tree — a group of players and coaches who have worked under him and now have coaching careers of their own.He’s worked at 12 clubs and national teams across seven countries so there have been quite a few that have been inspired by him. pic.twitter.com/cNyqBjThdv— Karan Tejwani (@karan_tejwani26) May 4, 2021One of the most crucial elements of the 4-1-4-1 formation is the defensive midfielder, who must be adept in supporting his forward colleagues in a high press, but doesn't leave his two central defenders exposed.Javi Martinez was renowned for playing this role effectively in the 4-1-4-1 employed by Bayern Munich.