With a pot of Premier League gold for the winners, it's little wonder the EFL Championship playoffs have a final known as "the richest game in football".

Former playoff winners Fulham have already been promoted to the top flight this season, leaving some of the second-tier sides behind them to engage in a nail-biting race to reach the end-of-season lottery.

Bournemouth beat Nottingham Forest to the second automatic promotion spot, meaning Huddersfield Town, Forest, Sheffield United and Luton Town contest the playoffs for the right to play Premier League football in 2022/23.

Huddersfield were the first team to book their spot at Wembley after Jordan Rhodes scored the decisive goal in a 2-1 aggregate win over Luton on Monday night.

In the other clash, Forest's playoff against Sheffield United needed to be settled on penalties with the sides level on 3-3 after 210 minutes of action as Forest goalkeeper Brice Samba saved three spot-kicks in the shoot-out.

How does the annual finale to the domestic English season work? Who will be at Wembley Stadium when two teams try to win promotion by the most dramatic of methods? Who's won there before? Here's what you need to know.

MORE: EFL Championship final day results: Sheffield United & Luton Town beat Millwall and Middlesbrough to playoffs

After the final day of the regular Championship season on May 7, Huddersfield Town, Nottingham Forest, Sheffield United and Luton Town were confirmed as the four sides to enter the playoffs.

Huddersfield snatched third place in the table after a 2-0 win over Bristol City, with Forest only able to draw 1-1 at Hull City. Sheffield United took fifth place after a 4-0 thrashing of champions Fulham, while Luton Town's 1-0 victory over Reading ensured they stayed in that top six.

Huddersfield and Luton headed into Monday's second-leg at The John Smith's Stadium tied at 1-1 and the home sided needed striker Rhodes to come to their rescue on 82 minutes with his strike sending them to Wembley.

Sheffield United trailed Forest 2-1 ahead of Tuesday night's second-leg but a 2-1 win for the visitors sent the tie to penalties at the City Ground. 

But the Blades failed to take their chances and a 3-2 win on penalties for Forest sparked jubilant scenes on the pitch from fans and players.

** = Won promotion * = In the playoffs

A post shared by Nottingham Forest FC (@officialnffc)

The teams finishing in the top two places in the division are automatically promoted to the Premier League. The teams finishing between from third to sixth enter the playoffs.

The side who finish third play those who came sixth, with fourth place facing fifth.

In each of these two-legged semi-final ties, the team that finished higher in the league table plays the second leg at home — a system designed to give them an advantage because of their superior league position.

If the aggregate score is level at the end of 90 minutes of the second leg, an extra 30 minutes are played to try to create a winning team. The contest is decided by a penalty shootout if the scores remain level after extra time.

The away goals rule, which has been used in past competitions to send the team with the most away goals over the two legs through if the aggregate score finishes level, is not applicable any longer.

The first semi-final first leg will took place on May 13, six days after the regular season concludes. The final will be held at Wembley Stadium, London, on May 29 where Huddersfield and Forest will battle it out for promotion.

While the familiar cliche that form goes out of the window under the pressure of the playoffs is not quite true - teams carrying momentum from the final stretch of the season have often won the final - the club finishing highest in the table has only been promoted in 13 of the 35 editions so far.

The outcomes since the format began in 1987, however, suggest that teams finishing 3rd are most likely to wind up celebrating in front of thousands of fans on the pitch at the national stadium — although that may be little consolation to supporters across the decades who have seen their teams suffer double agony after narrowly failing to go up automatically.

MORE: Which teams are in next season's Champions League? 

Teams that finish in the lowest position, sixth, fare weakest in the playoffs — despite a common belief that a late surge up the table can prove vital. Only five of them have proceeded to promotion, and none have done so since 2010.

The greatest challenge for teams who win the playoffs arrives immediately after promotion, as they have less time than their Premier League rivals to finalise bringing in reinforcements before taking the step up the following season.

It has been a mixed bag for playoff-winning teams in their first season in the Premier League after promotion in recent years: Hull City suffered immediate relegation in 2016 and Fulham have repeated the trick twice since then.

Huddersfield, however, survived a season among the elite, while Aston Villa have established themselves in the higher division and Brentford are almost certain to stay up this year after an impressive campaign.

* The first two seasons of the playoffs involved the Premier League (then known as the First Division) team immediately above the relegation places and the three Championship (then Second Division) clubs finishing below the automatic promotion places.

** Sunderland were subsequently promoted instead after Swindon were found guilty of illegal player payments.