Elf on the Shelf is the new Christmas craze sweeping parents and children across the globe.

As with Black Friday, the tradition has been imported from the US and adopted by parents in the UK in recent years.

However, some psychologists warned the idea of Santa sending a scout to watch over children could actually be harming and cause anxiety.

As we near Christmas day, here is everything you need to know about this growing holiday tradition.

What is Elf on the Shelf?

The original Elf on the Shelf is based on a book of the same name, written by Carole Aebersold and Chandra Bell and is designed to improve kids’ behaviour by encouraging them to stay on Santa’s "nice list".

Santa’s elves are said to have been dispatched from the North Pole to every home at the start of December to watch over children in the house.

Any undesirable behaviour is reported back to the big boss himself, who alters his naughty/nice list accordingly.

Over the years, the book has grown in popularity both in the US and the UK and has now become a tradition for a lot of families.

Meanwhile, retailers have turned the traditions in a merchandise opportunity.

Parents can now buy their own Elf on the Shelf from retailers across the UK such as Tesco for £31,95 or from the Elf on the Shelf’s official website from £29.95.

How does it work?

The idea is simple. Parents put the elf on a shelf in early December and inform their children that he will always be watching and judging them for signs of bad behaviour.

They are supposed to move the little toy around the house to create the illusion that he is popping up in different locations and always reporting back to Father Christmas

Christmas celebrations around the world Show all 30 1 /30 Christmas celebrations around the world Christmas celebrations around the world Virginia, USA A man dressed as Santa Claus water skis alongside reindeer on the Potomac River in Alexandra, Virginia. Christmas celebrations around the world Berlin, Germany A volunteer dressed in a Father Christmas (Santa Claus) outfit distributes gifts to children of asylum-seekers, as they arrive at the Schoenefeld train station near Berlin on December 24, 2015, before being dispatched to various refugee centres in or near the German capital. Christmas celebrations around the world Rio De Janeiro, Brazil Leandro Wendell dos Santos, 14, wearing a Santa Claus costume, plays with kids as he walks along the alley of the Mare slums complex to distribute presents to children in Rio de Janeiro, Brazil. Leandro is part of a volunteer group of residents of Mare slums complex that distributes donated toys to children of the community. 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Christmas celebrations around the world Cairns, Australia Bon Bon, a 12-month-old koala, celebrating with Christmas decorations at the Rainforestation Nature Park in Cairns, Australia, Christmas celebrations around the world Ayutthaya, Thailand A young Thai student wearing a Santa hat poses for a photograph during a Christmas event at a school in the world heritage city of Ayutthaya, north of Bangkok, Thailand, 24 December 2015. The annual event is one of many held to celebrate the Christmas season in predominantly Buddhist Thailand. Christmas celebrations around the world Colombo, Sri Lanka Sri Lankan pedestrians walk past a decorated Christmas tree in Colombo. The leader of Sri Lanka's Catholics urged priests on not to put up Christmas trees in their churches over the festive period, saying they had no religious significance. Sri Lanka is a mainly Buddhist country but around 1.2 million of its overall population of 21 million people are Catholics. Christmas celebrations around the world Seoul, South Korea Models wearing Santa Claus costumes wait to attend a special event to promote business in coincide with Christmas at Shinsegae department store in Seoul, South Korea. A lot of South Korean companies take advantage of the Christmas season to promote their business amid weak sales and economic slowdown. Christmas celebrations around the world Ayutthaya, Thailand A young Thai student wearing a Santa hat poses for a photograph during a Christmas event at a school in the world heritage city of Ayutthaya, north of Bangkok, Thailand, 24 December 2015. The annual event is one of many held to celebrate the Christmas season in predominantly Buddhist Thailand. Christmas celebrations around the world Oaxaca, Mexico Carved radishes are displayed during the celebration of the "Night of the Radishes" at the Ocototlan de Morelos community in Oaxaca State, Mexico. 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Posada Mexicana commemorates the journey of the Holy Family from Galilee to Bethlehem Christmas celebrations around the world Rio de Janeiro, Brazil Italian artist Gaspare di Caro, right, lights up Christ the Redeemer in Rio Reuters Christmas celebrations around the world Allahabad, India A view of All Saints Cathedral, decorated ahead of Christmas celebrations, in Allahabad Christmas celebrations around the world Guatemala City, Guatemala Firefighter Hector Chacon, centre, dressed as Father Christmas, delivers gifts to impoverished children after descending from a 150-metre bridge, behind Christmas celebrations around the world Karachi, Pakistan A Father Christmas is painted onto a wall in a Christian neighbourhood in Karachi Christmas celebrations around the world Valletta, Malta 3D projections designed by students of the Malta College of Arts, Science and Technology are projected onto the facade of the Presidential Palace Christmas celebrations around the world Moscow, Russia A snowman and Christmas tree erected in Red Square EPA Christmas celebrations around the world Taipei, Taiwan People crowd around for a view of a 3D Christmas tree erected in a shopping park EPA Christmas celebrations around the world Tokyo, Japan Cleaners dressed in a Father Christmas and a reindeer costume clean the windows of a shopping mall EPA Christmas celebrations around the world Shanghai, China A woman prays at the Shanghai International Chapel during a Christmas Eve Mass Reuters Christmas celebrations around the world A Bangladeshi man dressed as Father Christmas entertains children during an event to mark Christmas Day in Dhaka

Why could it be harmful?

If the idea of an Elf send by Santa himself could add to the magic of Christmas, some child experts warned that the concept could also cause fear and shame in children.

Ewan Gillon, a chartered psychologist and clinical director of First Psychology Scotland, told the Scotsman, that the idea of an elf that moves around the house, watching our every move, could cause “significant repercussions” for children.

He said: "The elf itself is one which most children usually consider a positive Christmas character; however they may start to feel uneasy knowing that it’s going to come ‘alive’ during the night and they won’t know when, or see it moving around.

"This unknown can cause real anxiety, especially those who may already have a fear of ‘haunted toys’, or toys they have seen come alive in films.”

Meanwhile, Dr Katherine Edward, a chartered and clinical psychologist, said the elf might prevent children from learning from their own mistakes.

She said: "The concern I would have with the “Elf” is the manner in which children might feel that they have ‘ruined’ something and cannot make it right if they show what is natural curiosity and pushing of boundaries".