It is a controversial topic, but love it or loathe it, there is no denying that the Eurovision Song Contest is watched by millions every year.

Here's everything you need to know about this year's competition.

What is Eurovision?

The Eurovision Song Contest is an annual singing competition which takes place in May.

It is usually only held between European countries but other countries, such as Australia, have also been invited to take part.

Each participating country submits an original song to be performed on live television and radio and then casts votes for the other countries' songs to determine the competition's winning entry.

The contest has been broadcast every year for sixty-two years, since its inauguration in 1956, and is one of the longest-running television programmes in the world.

It is also one of the most watched non-sporting events in the world, with audience figures in recent years quoted as anything between 100 million and 600 million internationally.

The idea behind the song contest was to bring European countries together in the aftermath of the Second World War and it has continued ever since.

When and where is it taking place?

This year, it will be held for the first time in Portugal following the country's first victory at the 2017 contest in Kiev, Ukraine with the song "Amar pelos dois", performed by Salvador Sobral.

It is taking place on Saturday.

How do countries qualify?

There are two semi-finals, taking place on May 8 and May 10.

Ten countries have qualified from the first semi-final. These are

For the semi-finals, the finalists were determined through a combination of televoting through the broadcast of the live show and the professional jury.

The nineteen countries participating in the first Semi-Final as well as Portugal, Spain and the United Kingdom could vote.

The ten finalists will participate in the Grand Final this Saturday alongside the ten countries who will qualify in the second semi-final this Thursday, as well as the ‘Big Five’ and host country Portugal.

The Big Five are the countries that make the biggest financial contribution to the competition, and this year are France, Germany, Italy, Spain and UK. They get through to the final automatically.

What is the UK's entry?

Surie represents the United Kingdom at the 2018 Eurovision Song Contest in Lisbon with the song Storm.

You can hear the song here:

How does voting in the final work?

Previously, voting was done by televote, but some countries found this unfair so recently it was changed to a new dual system.

A jury from each country award 1, 2, 3, 4, 5, 6, 7, 8, 10 and 12 points to their favourite songs, which is revealed in the original way.

Then, viewers can vote for their favourite songs by phone or SMS.

All the results from each country's public result are then combined to give overall Eurovision viewer score per song.

The Eurovision presenters read out the results of the European televote in ascending order, beginning with the country that received the lowest number of televotes and finishing with the country that received the highest.

Viewers in all the competing countries – including those who were knocked out in the semi-finals – can vote up to 20 times for the songs of their choice, but they can’t vote for their own country.

The country with the highest number of votes wins the competition and gets to host it the next year.

Who is favourite to win?

Currently Cyprus is favourite to win at 2/1, however close behind are Israel and Norway at 4/1.

The UK is a bit of an outsider at the moment at 200/1

Is it being shown on TV?

The grand final of Eurovision 2018 will be broadcast live at 8pm on May 12 on BBC One.

Graham Norton will provide the commentary from Lisbon for BBC viewers.