El Gordo – which translates as ‘The Fat One’ – is the undisputed largest lottery in the world in terms of the total prize money on offer.
The top prize is £355,000, but although other lottery draws have a much more substantial grand prize, El Gordo has a total fund of £2bn (€2.3bn) – the largest anywhere in the world.
However the draw is governed by a complex set of rules, which state 70 per cent of the money people have spent on tickets must be distributed as prizes, with the rest kept by the state and official ticket sales.
The format is also unique. Emulating something more like an old school raffle, lines are sold with different numbers with each line consisting of five digits. For example, 12345.
Tickets are printed in series of hundreds which means there could be dozens of other people with the exact same numbers – and all could potentially share the massive prize.
The hugely popular draw first took place in 1812 and has been held on 22 December every year since.
Today’s draw is expected to take place at 4pm.
Standard tickets cost €200 (£177) but people traditionally pool resources and buy shares in multiple tickets with friends, family or workmates.
Or customers can opt in and spend €20 (£17) on a one-tenth share of a ticket.
Spaniards spend an average of €55 (£49) on tickets each year, according to reports.
Prize numbers will be drawn today by children from a Madrid school, who will sing the winning numbers in a bizarre tradition.
Traditionally betting on the Spanish Christmas Lottery was for residents of Spain only, but luckily, times have changed.