Video assistant referees, or VAR, have been at the centre of plenty of talking points since they were introduced to the Premier League at the start of the season.

Here, the PA news agency looks at some of the key issues surrounding the technology following its first month of use in the top flight.

What decisions is VAR assisting with?

In accordance with rules set down by the International Football Association Board (IFAB), VAR is concerned with looking at four key areas: goal/no goal, penalty/no penalty, direct red cards and cases of mistaken identity. These areas are automatically reviewed irrespective of the referee's decision.

How does it work?

A VAR room based at Stockley Park in west London covers every top-flight game and has a team of at least three people working with the match officials. The VAR, an assistant VAR and a Hawkeye operator are in constant communication with officials at the ground and ensure the right camera angles are made available to assist in the decision-making process.

How many decisions have been corrected so far?

In the 40 Premier League games played before the international break, there have been six occasions when an initial refereeing decision has been changed on review. Five of those have been to disallow goals – two for offside, two for handball and one for a foul. VAR has, so far, not awarded a penalty or a red card, although it did order a retaken spot-kick for Manchester City due to encroachment from West Ham's Declan Rice.

How has VAR been received?

VAR has sparked plenty of debate already this season and seems to be a constant talking point. While there have been many supporting the introduction of the technology with a view to eradicating errors, others have accused it of taking the initial joy out of goals and killing the game. Fans attending matches have also been left wondering why some decisions have or have not been overturned. Former Premier League referee Keith Hackett has called the current situation "untenable", adding that a lack of consistency is making referees look "foolish".

Why have some seemingly incorrect decisions not been overturned?

Because Premier League VAR operates with a high threshold for intervention on subjective decisions. David Silva, Harry Kane and Sebastien Haller are among the players to have strong penalty appeals waved away by referees and not overturned on review, while Leicester midfielder Youri Tielemans on Saturday escaped a red card following a reckless challenge on Bournemouth's Callum Wilson. Kurt Zouma's disallowed goal in Chelsea's win at Norwich is so far the only subjective decision overturned by VAR due to Olivier Giroud's foul on Tim Krul. PA understands there are no current plans to lower the threshold.

Are there any examples when VAR has been unable to intervene?

Yes. Aston Villa were denied a late equaliser in Saturday's 1-0 defeat at Crystal Palace after referee Kevin Friend harshly penalised Jack Grealish for a supposed dive seconds before Henri Lansbury found the net. Although the decision has been widely criticised by pundits and supporters, VAR was powerless to award the goal as the match official had already blown his whistle to halt play – though Grealish could have been given a penalty.

Which team has suffered the most so far?

Despite benefiting from Sergio Aguero's retaken penalty against West Ham, champions City have had two goals chalked off, both scored by Gabriel Jesus. The first came at the London Stadium when Raheem Sterling was adjudged to be marginally offside in the build-up, with the second causing Pep Guardiola's side to drop two points after Aymeric Laporte was penalised for handball after Jesus thought he had found a winner in the 2-2 draw with Tottenham. Wolves, Brighton and Chelsea have also had goals disallowed by VAR.

Will any changes be made during the international break?

It seems incredibly unlikely. PA understands that PGMOL is generally pleased with how the technology has so far been used and does not intend to make alterations based on knee-jerk reactions. A meeting of Premier League shareholders is scheduled to take place later this month, with VAR certain to be on the agenda.