Paul Moss

Rob Stephens.

It's known as El Gordo, literally the fat one, Spain's annual Christmas lottery, with the world's largest lottery jackpot.

It's a cherished tradition, more than 200 years old, and the winner will be announced later on Monday, with more than $3 billion now up for grabs.

Carla Conti reports.

In Spain, it's not just the winter markets or dazzling light displays on busy streets that set the tone for the festive season, but the much-awaited Lotería de Navidad, the country's annual Christmas lottery.

Better known as El Gordo, or the Fat One, it is the biggest lottery in the world in terms of total prize money, with approximately $3.2 billion to be shared out.

The lottery is based on a five-digit number, and each number is printed many times, so lots of people can end up holding the same one.

A full ticket, or billete, costs 200 euros, just over 200 dollars, but most people buy a decimo, literally a tenth of a ticket, which costs 20 euros.

And it's not just about the jackpot.

There are lots of smaller prizes too, so some tickets win more modest amounts.

That's why you'll often see friends, families or whole workplaces club together, buying strips of decimos, so if their number comes up, everyone gets a share.

In the months leading up to the draw, that shared anticipation grows everywhere.

Then, every 22nd of December, pretty much the whole of Spain tunes into a four-hour TV extravaganza broadcast live from Madrid's Teatro Real Opera House.

During the programme, young schoolchildren pick the winning numbers from two large spinning globes and sing them out to the crowd.

For Spaniards, it's an instantly recognisable sound, and it's how millions of people find out in real time whether they've won.

And once the final prizes are announced, the broadcast often cuts straight to the places that sold the winning numbers, where people can be seen flooding the streets and popping champagne bottles outside lottery shops.

By lunchtime, the draw is over, but the conversation isn't.

People compare what they won, mourn their losses, and think about whether they'll buy in again next year.

And of course, plenty of people get nothing at all.

But the tradition of El Gordo endures because of what it brings to Spain, a shared sense of community.