Last week, Britain crowned a king. This week, it will help bestow Europe’s pop crown.

The Eurovision Song Contest is returning to the U.K. for the first time in 25 years, but the heart of the glitzy music competition will be in Ukraine.

Britain is hosting the event on behalf of the war-battered country, and organizers have vowed to make it a celebration of Ukrainian spirit and culture.

The contest will see musical acts from 37 countries perform original songs in the English city of Liverpool, with semi-finals Tuesday and Thursday and a grand final on Saturday watched by an estimated 160 million people.

For fans and first-timers alike, here’s an essential Eurovision guide:

WHAT IS EUROVISION, ANYWAY?

First staged in 1956, Eurovision was founded to help unite a shattered continent after World War II and to test nascent live-broadcasting technology.

Initially a sedate affair featuring crooners in ballgowns and tuxedos, it began to let its hair down during the swinging 60s and reached pop perfection in 1974, when ABBA won with “Waterloo,” propelling the band toward superstardom and jump-starting Sweden’s music industry.

Since then, the contest has expanded across Europe and beyond – Israel and Australia are both entrants – with ever-more elaborate staging and eye-popping costumes.

Eurovision also has become a celebration of diversity, with a huge LGBTQ+ following that celebrated when Israel’s Dana International became the contest’s first transgender winner in 1998.

Above all, the competition is a crash course in the continent’s wonderfully varied musical tastes. Winners have ranged from Canadian chanteuse Celine Dion, who competed for Switzerland in 1988, to fright mask-wearing Finnish metalheads Lordi in 2006 and bearded Austrian drag performer Conchita Wurst in 2014.

Last year, Ukrainian folk-rap band Kalush Orchestra triumphed, delivering a morale boost for a country battling Russia’s invasion.

Paul Jordan, an expert on the contest who is known as “Dr. Eurovision,” said the competition has become a treasured part of European culture.

“You can go to Spain, Slovenia, wherever — everyone’s heard of it,” he said. “They may not love it, they may not like it, they may not watch it, but everyone’s heard of it. Everyone’s got an opinion. I think it’s really powerful, and it’s a brilliant icebreaker.”

WHERE POP MEETS POLITICS

Eurovision is about much more than music. It’s diplomacy with a disco beat, a forum in which countries can boost their profiles and play out regional rivalries.

Organizers strive to keep pop and politics apart; overtly political symbols and lyrics are prohibited. But global tensions have often imposed themselves on the contest. Ukraine has several times used its entries to criticize Russia, winning in 2016 with a song about the expulsion of Crimea’s Tatars by Stalin in 1944.

Russia was banned from the contest last year after it invaded Ukraine. Belarus had been kicked out the previous year over its government’s clampdown on dissent.

Dean Vuletic, an academic expert on Eurovision, said that by banning Russia, Eurovision lost one of its biggest national audiences and “one of its most enthusiastic participants.”

“But Eurovision is also a platform on which values are expressed, around which values are constructed,” Vuletic said, and pressure from member nations forced the European Broadcasting Union, which runs Eurovision, to act.

Eurovision “has always reflected cultural, political and social change in Europe,” he said. “(It’s) a way to measure the zeitgeist in Europe.”

A MUSICAL MELANGE

Eurovision was long associated with fluffy 3-minute pop songs — previous winners include the likes of “La, La, La” and “Boom Bang-a-Bang.”

But Vuletic says it’s no longer “the contest with silly songs, innocuous lyrics that it perhaps used to be.” He says a third of this year’s entries deal lyrically with “toxic relationships, anxiety” and other mental-health issues. Another batch of songs are about war.

Musically, contestants range from pop ballads like “Power” by Iceland’s Diljá and relationship-breakup dance track “I Wrote a Song” by Britain’s Mae Muller to the electronica of “Heart of Steel” by Ukraine’s Tvorchi. Austrian duo Teya & Salena offer an offbeat tribute to Edgar Allen Poe, “Who the Hell is Edgar?” while Croatia’s Let 3 belts out antiwar rock opera “Mama ŠČ!”

Eurovision’s complex voting system, which awards points from juries of music industry professionals as well as viewers across Europe, makes winners notoriously hard to predict.

Bookmakers’ favorites include Finnish entry Käärijä’s pop-metal party tune “Cha Cha Cha” and power ballad “Tattoo” by Sweden’s Loreen, who previously won the contest in 2012. Singer La Zarra, competing for France, is also highly ranked for her Edith Piaf-esque chanson “Évidemment.”

U.K.-UKRAINE FUSION

The U.K. stepped in to host the contest for Ukraine after last year’s British entry, Sam Ryder, finished second. As Ryder put it: “It’s Ukraine’s party. We’re just inviting them to throw it at our house.”

The final will be co-hosted by Ukrainian singer Julia Sanina and will feature a performance by Kalush Orchestra and other representatives of Ukrainian culture. Several thousand Ukrainian refugees in Britain have received tickets to attend.

Ryder’s strong showing last year with “Spaceman” helped transform Eurovision’s image in the U.K. Long viewed as a guilty pleasure – amid perennial grumbling over the country’s poor results — it now a source of pride and celebration.

Several U.K. cities competed to host the event, and winner Liverpool is in party mood. The port city that gave birth to The Beatles went through tough times as U.K. industry collapsed in the late 20th century. It has since reinvented itself as a hub for sports, culture and nightlife – a resilience that fits well with Ukraine, Jordan says.

“It’s a real creative hub, and I think it’s going to be a brilliant host city — apart from the weather,” he said.